Processing method of corrosion-resistant composite pipe with high bonding strength and high heat exchange performance

Abstract

The invention provides a processing method of a corrosion-resistant composite pipe with high bonding strength and high heat exchange performance. The method comprises the following steps: uniformly spraying silver solder on the outer surface of an inner pipe; the inner pipe sprayed with the silver solder is sleeved with the outer pipe for cold rolling, and an initial composite pipe is obtained; and the initial composite pipe is placed in a vacuum environment to be subjected to diffusion welding heat treatment, and the composite pipe is obtained. By adopting the silver solder as the middle layer, not only is tight compounding between copper pipes or titanium pipes realized, but also the bonding strength of the composite pipe is remarkably improved. The silver solder has excellent wettability and flowability, and can be uniformly distributed between the inner pipe and the outer pipe in the cold rolling process to form a compact bonding interface.

Description

Technical Field

[0001] The present invention relates to the technical field of pipe manufacturing, and particularly to a processing method for a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance. Background Art

[0002] In industrial fields such as energy chemistry and aerospace, the performance of heat exchangers is directly related to production efficiency and cost control. For traditional heat exchanger pipes, such as copper alloys and stainless steels, when working in a corrosive medium environment with high concentrations of Cl-, H+, etc., pitting corrosion will occur on the side in contact with the corrosive medium within a short time and quickly perforate and fail, resulting in pipeline leakage and equipment failure, thereby reducing the safety and economic benefits of the equipment. To solve the problem of pipeline corrosion failure, traditional methods usually use pure titanium pipes as substitute materials. However, due to the low thermal conductivity of pure titanium, the heat exchange efficiency of the heat exchanger is greatly reduced, resulting in increased equipment energy consumption and inability to meet the performance requirements of high efficiency and energy conservation. At the same time, limited by the heat exchange efficiency, the volume and weight of titanium pipe heat exchanger equipment are relatively large. Correspondingly, the supporting costs for materials, transportation, civil engineering, etc. are high.

[0003] If two types of pipes can be compounded to create a composite pipe with the advantages of both, the corrosion resistance can be greatly improved while maintaining strong heat exchange performance, ensuring long-term stable operation. However, due to the significant differences in the lattice structure, atomic radius, and chemical activity between copper and titanium, the interfacial bonding force is weak during direct compounding, and delamination is likely to occur, seriously affecting the performance and application of the pipe. Currently, although there are some technologies for metal composite pipes, there are significant limitations in solving the interfacial problems of copper-titanium compounding and improving comprehensive performance. For example, traditional drawing techniques for compounding result in extremely low interfacial bonding strength. Summary of the Invention

[0004] The present invention aims to at least solve the technical problem of low interfacial bonding strength in the prior art, and particularly innovatively proposes a processing method for a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance.

[0005] To achieve the above object of the present invention, the present invention provides a processing method for a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance, and the method includes:

[0006] Uniformly spray silver solder on the outer surface of the inner pipe;

[0007] Put the inner pipe sprayed with silver solder into the outer pipe for cold rolling to obtain an initial composite pipe;

[0008] Place the initial composite pipe in a vacuum environment for diffusion welding heat treatment to obtain a composite pipe.

[0009] As an alternative embodiment of the present invention, optionally, the inner pipe is a copper pipe or a titanium pipe; the outer pipe is a copper pipe or a titanium pipe.

[0010] As an alternative embodiment of the present invention, optionally, during the cold rolling process, the rolling speed is 0.5 m / s and the reduction per pass is 5%.

[0011] As an alternative embodiment of the present invention, optionally, the degree of vacuum in the vacuum environment is below 10 -3 Pa.

[0012] As an alternative embodiment of the present invention, optionally, in the diffusion welding heat treatment, the heating temperature and the applied welding pressure are periodically changed.

[0013] As an alternative embodiment of the present invention, optionally, the difference between the inner diameter of the outer pipe and the outer diameter of the inner pipe is between 0.86 mm and 0.90 mm.

[0014] As an alternative embodiment of the present invention, optionally, the method further includes cleaning the welding surfaces of the titanium pipe and the copper pipe.

[0015] As an alternative embodiment of the present invention, optionally, the cleaning treatment of the welding surfaces includes a degreasing process, a degreasing process and a deoxidation process.

[0016] As an alternative embodiment of the present invention, optionally, the degreasing process, the degreasing process and the deoxidation process for the titanium pipe include:

[0017] Immerse the titanium pipe in an alkaline etching solution at 55 °C for more than 20 minutes;

[0018] Rinse the surface of the titanium pipe with deionized water and perform a drying treatment.

[0019] As an alternative embodiment of the present invention, optionally, the degreasing process, the degreasing process and the deoxidation process for the copper pipe include:

[0020] Immerse the copper pipe in a mixed solution of an acid cleaning agent and a surfactant prepared in proportion at 40 °C for more than 15 minutes;

[0021] Rinse the surface of the copper pipe with deionized water and perform a drying treatment.

[0022] The beneficial effects of the present invention are that by using a silver solder as an intermediate layer, not only the tight composite between the copper pipe or the titanium pipe is realized, but also the bonding strength of the composite pipe is significantly improved. The silver solder has excellent wettability and fluidity, and can be evenly distributed between the inner and outer pipes during the cold rolling process to form a dense bonding interface.

[0023] The present invention enables the composite pipe to efficiently transfer heat through the good thermal conductivity of copper and silver, greatly improving the overall heat exchange efficiency and meeting the requirements of heat exchange equipment for efficient heat transfer.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Brief Description of the Drawings

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0026] Figure 1 is a flowchart of a processing method for a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance according to the present invention. Detailed Description of the Embodiments

[0027] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0028] As Figure 1 shown, a processing method for a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance, the method comprising:

[0029] S1. Uniformly spray a silver solder on the outer surface of the inner pipe;

[0030] The inner pipe here can be a copper pipe or a titanium pipe. Here, the inner pipe is selected as a copper pipe. Before spraying the silver solder on the outer surface of the inner pipe (copper pipe), the copper pipe needs to be pretreated. The pretreatment of the copper pipe includes degreasing, defatting and deoxidation processes. Specifically, a mixed solution containing a specific proportion of acidic cleaning agent and surfactant is used to soak the copper pipe at 40 °C for 15 minutes to remove the surface oil stain and oxide layer. Subsequently, the copper pipe is rinsed clean with deionized water and dried to ensure that the surface of the pipe is clean and free of impurities, providing a good basis for subsequent spraying of the silver solder. When uniformly spraying the silver solder on the outer surface of the inner pipe, a high-precision spraying device is used, and thermal spraying technology is adopted. The distance between the spray gun and the pipe surface is controlled at 200 mm, the spraying air pressure is 0.4 MPa, and the spraying thickness is accurately controlled within a certain range according to the design requirements of the pipe and the actual working conditions, and the deviation can be controlled within ±0.01 mm to ensure uniform coverage of the silver solder and provide a transition medium for the copper-titanium combination.

[0031] S2. Fit the inner pipe sprayed with the silver solder into the outer pipe and perform cold rolling to obtain an initial composite pipe;

[0032] The outer pipe material here can be copper pipe or titanium pipe. Since copper pipe is selected in the above S1, titanium pipe is selected as the outer pipe material here; before cold rolling, the titanium pipe needs to be further pretreated, and the pretreatment includes degreasing, de-fatting and deoxidation processes. Specifically, it is treated with an alkaline etching solution, soaked at 55°C for 20 minutes to remove surface impurities and oxide film, and then rinsed and dried with deionized water. Ensure that the pipe surface is clean and free of impurities, providing a good foundation for the subsequent cold rolling process. During cold rolling, the copper pipe sprayed with silver solder and pretreated is sleeved with the pretreated titanium pipe for cold rolling processing. During the cold rolling process, the rolling speed is precisely controlled at 0.5m / s, the reduction per pass is 5%, and the rolling temperature is room temperature, so that the inner and outer layer pipes are initially bonded, reducing the wall thickness deviation of the pipes, improving the dimensional accuracy and surface quality of the pipes, and making the roundness deviation of the pipes controllable within ±0.1mm.

[0033] S3. Place the initial composite pipe in a vacuum environment for diffusion welding heat treatment to obtain a composite pipe.

[0034] Put the cold-rolled composite pipe into a vacuum environment for diffusion welding heat treatment. The vacuum degree is controlled below 10 -3 Pa. Pulse heating and dynamic pressure control technologies are adopted to periodically change the heating temperature and applied pressure during the welding process. For example, the heating temperature periodically changes between 800-850°C, and the pressure periodically changes between 5-6MPa, promoting the atomic diffusion and metallurgical reaction of silver solder with copper and titanium, realizing the metallurgical bonding of copper and titanium, and significantly improving the bonding strength of the composite pipe.

[0035] The above is divided into two structures: copper inside and titanium outside, and copper outside and titanium inside. The copper-inside-and-titanium-outside structure is suitable for the working conditions where the outside contacts corrosive media and the inside circulates heat exchange refrigerant; the copper-outside-and-titanium-inside structure is suitable for the working conditions where the inside contacts corrosive media and the outside is used for heat exchange. Silver solder, as a transition layer, fills the gap between copper and titanium and forms a firm metallurgical structure through metallurgical reaction to ensure the tight bonding of copper and titanium. In the design of the inner and outer layer pipe sizes, the inner diameter of the outer layer pipe is about 0.8mm larger than the outer diameter of the inner layer pipe, which is convenient for sleeving processing.

[0036] In the above step S1, silver solder is innovatively used as the transition layer. Utilizing the ultra-high thermal conductivity, good wettability and gap filling ability of silver, it can not only form a firm metallurgical structure between copper and titanium, solve the interface bonding problem, but also greatly improve the overall thermal conductivity of the pipe, which is difficult to achieve simultaneously by other transition layer materials in the existing technology.

[0037] Based on the traditional processes of nesting, cold rolling, and vacuum diffusion welding, fine control and innovative improvements have been made to each link. For example, in the pretreatment link, different degreasing, defatting, and deoxidation processes are adopted according to the different surface characteristics of copper and titanium to ensure that the surface cleanliness and activity reach the best state, laying a good foundation for subsequent silver solder spraying and compounding. During the silver solder spraying process, high-precision spraying equipment and process parameters are used to achieve precise control of the silver solder thickness, ensuring the uniformity and stability of the silver solder layer. In the cold rolling process, by optimizing parameters such as rolling speed, reduction per pass, and rolling temperature, the tight bonding of the inner and outer layer tubes is achieved, while improving the dimensional accuracy and surface quality of the tubes, and the roundness deviation of the tubes can be controlled within ±0.1 mm. In the vacuum diffusion welding link, pulse heating and dynamic pressure control technologies are innovatively adopted, and the heating temperature and applied pressure are periodically changed during the welding process to promote the atomic diffusion and metallurgical reaction between the silver solder and copper-titanium, forming a more uniform and firm bonding layer, effectively improving the bonding strength and comprehensive performance of the composite tubes.

[0038] The above designs two unique structures of inner copper outer titanium and outer copper inner titanium, and optimally matches parameters such as the wall thickness and outer diameter of the inner and outer layer tubes according to different working conditions and tube sizes. In addition, through theoretical calculation and experimental verification, an optimization model of tube structure parameters can be established, which can quickly and accurately determine the best tube structure parameters according to specific usage scenarios and performance requirements, realizing the maximum utilization of tube performance. For example, for tubes with an inner copper outer titanium structure, when used in the working condition where the outer side contacts a strong corrosive medium and the inner side circulates heat exchange refrigerant, according to parameters such as the concentration and temperature of the corrosive medium and the flow rate and temperature of the heat exchange refrigerant, the optimization model is used to determine the best wall thickness and outer diameter of the inner copper tube and the outer titanium tube, which can not only ensure the corrosion resistance of the tubes but also ensure good heat exchange efficiency.

[0039] The good thermal conductivity of copper and silver enables the composite tubes to transfer heat efficiently, greatly improving the overall heat exchange efficiency, which is 20%-30% higher than that of traditional copper-titanium composite tubes, meeting the requirements of heat exchange equipment for high-efficiency heat transfer.

[0040] The corrosion resistance of titanium enables the composite tubes to operate stably for a long time under working conditions with corrosive media. After simulation experiment verification, in corrosive media such as strong acids and alkalis, the corrosion-resistant life of the tubes is extended compared with ordinary tubes, broadening the application range of the tubes and reducing the equipment maintenance cost.

[0041] The metallurgical structure formed by the silver solder effectively solves the interface bonding problem during the direct compounding of copper and titanium. The bonding strength is improved compared with the existing technology, preventing delamination and ensuring the reliability and service life of the tubes.

[0042] Through process optimization and innovation, while ensuring the performance of the pipe, the production cost is reduced, the production efficiency is improved, the production cycle is shortened, and it is more suitable for large-scale industrial production.

[0043] As an alternative embodiment of the present invention, optionally, the inner pipe is a copper pipe or a titanium pipe; the outer pipe is a copper pipe or a titanium pipe.

[0044] As an alternative embodiment of the present invention, optionally, during the cold rolling process, the rolling speed is 0.5 m / s and the reduction per pass is 5%.

[0045] As an alternative embodiment of the present invention, optionally, the degree of vacuum in the vacuum environment is below 10 -3 Pa.

[0046] As an alternative embodiment of the present invention, optionally, in the diffusion welding heat treatment, the heating temperature and the applied welding pressure are periodically changed.

[0047] As an alternative embodiment of the present invention, optionally, the difference between the inner diameter of the outer pipe and the outer diameter of the inner pipe is between 0.86 mm and 0.90 mm.

[0048] As an alternative embodiment of the present invention, optionally, the method further includes cleaning the welding surface of the titanium pipe and the copper pipe.

[0049] As an alternative embodiment of the present invention, optionally, the welding surface cleaning treatment includes degreasing process, degreasing process and deoxidation process.

[0050] As an alternative embodiment of the present invention, optionally, the degreasing process, degreasing process and deoxidation process for the titanium pipe include:

[0051] Immerse the titanium pipe in an alkaline etching solution at 55 °C for more than 20 minutes;

[0052] Rinse the surface of the titanium pipe with deionized water and perform a drying treatment.

[0053] As an alternative embodiment of the present invention, optionally, the degreasing process, degreasing process and deoxidation process for the copper pipe include:

[0054] Immerse the copper pipe in a mixed solution of acid cleaning agent and surfactant prepared in proportion at 40 °C for more than 15 minutes;

[0055] Rinse the surface of the copper pipe with deionized water and perform a drying treatment.

[0056] (I) Embodiment 1

[0057] Pipe structure: copper inner layer and titanium outer layer. The outer diameter of the inner copper pipe is 20 mm and the wall thickness is 2 mm; the outer diameter of the outer titanium pipe is 21.6 mm and the wall thickness is 1.5 mm.

[0058] Silver solder spraying: The spraying thickness of silver solder is 0.05 mm, and a silver-copper-zinc alloy solder with a silver content of 50% is selected.

[0059] Vacuum diffusion welding parameters: welding temperature 800 °C, pressure 5 MPa, heat preservation time 60 min. Pulse heating and dynamic pressure control technologies are adopted, and the heating temperature changes periodically between 800 - 820 °C, and the pressure changes periodically between 5 - 5.2 MPa.

[0060] Performance test: After testing, the bonding strength of the composite pipe reaches 350 MPa, the thermal conductivity is 380 W / (m·K), and there is no obvious corrosion sign on the outer wall after being immersed in the simulated corrosive medium for 30 days.

[0061] Example 2

[0062] Pipe structure: copper outer layer and titanium inner layer. The outer diameter of the outer copper pipe is 30 mm and the wall thickness is 3 mm; the outer diameter of the inner titanium pipe is 29.2 mm and the wall thickness is 2 mm.

[0063] Silver solder spraying: The spraying thickness of silver solder is 0.08 mm, and a silver-copper-zinc-cadmium alloy solder with a silver content of 45% is selected.

[0064] Vacuum diffusion welding parameters: welding temperature 850 °C, pressure 6 MPa, heat preservation time 45 min. Pulse heating and dynamic pressure control technologies are adopted, and the heating temperature changes periodically between 830 - 850 °C, and the pressure changes periodically between 5.8 - 6 MPa.

[0065] Performance test: The bonding strength of the composite pipe reaches 380 MPa, the thermal conductivity is 360 W / (m·K), and it shows good corrosion resistance and heat transfer performance in actual working conditions. There is no obvious corrosion sign on the inner wall of the pipe after being immersed in the simulated corrosive medium for 30 days.

[0066] Example 3

[0067] Pipe structure: copper inner layer and titanium outer layer. The outer diameter of the inner copper pipe is 15 mm and the wall thickness is 1.5 mm; the outer diameter of the outer titanium pipe is 16.6 mm and the wall thickness is 1.2 mm.

[0068] Silver solder spraying: The spraying thickness of silver solder is 0.06 mm, and a silver-copper alloy solder with a silver content of 60% is selected.

[0069] Vacuum diffusion welding parameters: welding temperature 820 °C, pressure 5.5 MPa, holding time 50 min. Pulse heating and dynamic pressure control technologies are adopted, and the heating temperature varies periodically between 810 - 830 °C, and the pressure varies periodically between 5.3 - 5.5 MPa.

[0070] Performance test: The bonding strength of the composite pipe reaches 320 MPa, the thermal conductivity is 390 W / (m·K). The outer wall of the pipe operates in a simulated acidic corrosion environment for 30 days, and the pipe performance is stable. The production cycle is shortened by 18% compared with the traditional process.

[0071] Example 4

[0072] Pipe structure: copper outer and titanium inner. The outer diameter of the outer copper pipe is 25 mm, and the wall thickness is 2.5 mm; the outer diameter of the inner titanium pipe is 24.2 mm, and the wall thickness is 1.8 mm.

[0073] Silver solder spraying: The spraying thickness of the silver solder is 0.1 mm, and a silver-copper-tin alloy solder with a silver content of 40% is selected.

[0074] Vacuum diffusion welding parameters: welding temperature 880 °C, pressure 7 MPa, holding time 30 min. Pulse heating and dynamic pressure control technologies are adopted, and the heating temperature varies periodically between 860 - 880 °C, and the pressure varies periodically between 6.8 - 7 MPa.

[0075] Performance test: The bonding strength of the composite pipe reaches 400 MPa, the thermal conductivity is 350 W / (m·K). When used in a corrosion medium containing chloride ions, no corrosion perforation phenomenon occurs, and the production cost is reduced by 15% compared with the traditional process.

[0076] (II) Comparative examples

[0077] Comparative example 1 (without silver transition layer)

[0078] Pipe structure: copper inner and titanium outer. The outer diameter of the inner copper pipe is 20 mm, and the wall thickness is 2 mm; the outer diameter of the outer titanium pipe is 21.6 mm, and the wall thickness is 1.5 mm.

[0079] Preparation method: Directly sleeve and cold roll the copper and titanium pipes and then perform vacuum diffusion welding without a silver solder transition layer.

[0080] Performance test: The bonding strength is only 100 MPa, far lower than that of Example 1, and delamination is likely to occur during subsequent use. The thermal conductivity is 200 W / (m·K), and the heat transfer efficiency is low, unable to meet the actual requirements.

[0081] Comparative example 2 (nickel transition layer)

[0082] Pipe structure: copper inner layer and titanium outer layer. The outer diameter of the inner copper pipe is 20 mm and the wall thickness is 2 mm; the outer diameter of the outer titanium pipe is 21.6 mm and the wall thickness is 1.5 mm.

[0083] Interlayer treatment: Nickel is used as the interlayer, and nickel is electroplated on the surface of the copper pipe. The thickness of the nickel layer is 0.05 mm.

[0084] Performance test: The bonding strength is 200 MPa and the thermal conductivity is 300 W / (m·K). Although there is a certain bonding effect, the thermal conductivity is lower than that of Example 1.

[0085] Comparative Example 3 (aluminum interlayer)

[0086] Pipe structure: copper inner layer and titanium outer layer. The outer diameter of the inner copper pipe is 20 mm and the wall thickness is 2 mm; the outer diameter of the outer titanium pipe is 21.6 mm and the wall thickness is 1.5 mm.

[0087] Interlayer treatment: Aluminum is used as the interlayer, and an aluminum layer is formed on the surface of the copper pipe by hot dip plating. The thickness of the aluminum layer is 0.05 mm.

[0088] Performance test: The bonding strength is low, only 80 MPa.

[0089] Comparative Example 4 (silver layer thickness beyond the range)

[0090] Pipe structure: copper inner layer and titanium outer layer. The outer diameter of the inner copper pipe is 20 mm and the wall thickness is 2 mm; the outer diameter of the outer titanium pipe is 21.6 mm and the wall thickness is 1.5 mm.

[0091] Silver solder spraying: The thickness of the silver solder spraying is 0.2 mm, far exceeding the normal design range.

[0092] Performance test: The bonding strength is 250 MPa. Due to the excessive thickness of the silver layer, a large number of brittle phases are generated during the vacuum diffusion welding process, resulting in a decrease in the toughness of the pipe. Cracks are likely to appear during actual use, and the production cost increases while the economic benefit decreases.

[0093] Comparative Example 5 (welding temperature beyond the range)

[0094] Pipe structure: copper inner layer and titanium outer layer. The outer diameter of the inner copper pipe is 20 mm and the wall thickness is 2 mm; the outer diameter of the outer titanium pipe is 21.6 mm and the wall thickness is 1.5 mm.

[0095] Vacuum diffusion welding parameters: The welding temperature is 950 °C, far exceeding the normal process temperature.

[0096] Performance test: The bonding strength is 220 MPa. The excessive temperature causes excessive reaction between copper, titanium and silver solder, forming a large number of brittle compounds. The thermal conductivity and corrosion resistance of the pipe are both negatively affected, and the heat transfer efficiency decreases, unable to meet the requirements of actual working conditions.

[0097] Performance test results:

[0098]

[0099]

[0100] In summary, from the above performance test results, it can be seen that the embodiment using silver solder as the transition layer is significantly superior to the comparative examples without a transition layer or using other transition layers in terms of bonding strength, thermal conductivity, and overall performance. Especially under working conditions with strong corrosive media and high requirements for heat transfer efficiency, the composite pipes with a silver solder transition layer exhibit more stable and excellent performance. At the same time, through the fine control and optimization of each preparation link, the maximum performance of the pipes is achieved, providing a reliable solution for industrial applications. Therefore, the processing method of the corrosion-resistant composite pipes with high bonding strength and strong heat transfer performance of the present invention has significant technical advantages and application prospects.

[0101] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for processing a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance, characterized in that: The method comprises: Spray silver solder evenly on the outer surface of the inner pipe; The inner tube sprayed with silver solder is placed inside the outer tube for cold rolling to obtain an initial composite tube; The initial composite pipe is placed in a vacuum environment for diffusion welding heat treatment to obtain a composite pipe.

2. The method for processing a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance according to claim 1, characterized in that: The inner tube is a copper tube or a titanium tube; the outer tube is a copper tube or a titanium tube.

3. The method for processing a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance according to claim 2, characterized in that: During the cold rolling process, the rolling speed was 0.5 m / s and the pass reduction was 5%.

4. The method for processing a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance according to claim 2, characterized in that: The vacuum degree of the vacuum environment is 10 -3 Below Pa.

5. The method for processing a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance according to claim 2, characterized in that: In the diffusion welding heat treatment, the heating temperature and the applied welding pressure are periodically changed.

6. The method for processing a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance according to claim 2, characterized in that: The difference between the inner diameter of the outer tube and the outer diameter of the inner tube is between 0.86 mm and 0.90 mm.

7. The method for processing a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance according to claim 2, characterized in that: The method further comprises cleaning the welding surfaces of the titanium tube and the copper tube.

8. The method for processing a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance according to claim 7, characterized in that: The welding surface cleaning process includes a degreasing process, a degreasing process and a deoxidation process.

9. The method for processing a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance according to claim 8, characterized in that: The degreasing process, degreasing process and deoxidation process for titanium tubes include: Soak the titanium tube in 55°C alkaline etching solution for more than 20 minutes; Rinse the surface of the titanium tube with deionized water and dry it.

10. The method for processing a corrosion-resistant composite pipe with high bonding strength and strong heat exchange performance according to claim 8, characterized in that: The degreasing process, degreasing process and deoxidation process for copper tubes include: Soak the copper tube in a mixed solution of an acidic cleaning agent and a surfactant prepared in proportion at 40°C for more than 15 minutes; Rinse the surface of the copper tube with deionized water and dry it.

Images