A method for manufacturing an aluminum-based composite pipe

Abstract

The present invention discloses a method for manufacturing an aluminum-based composite pipe, comprising the following steps: Step 1: adding a homogeneous blending agent of 1-5% of the total amount of liquid aluminum alloy to a 7-series or 4-series liquid aluminum alloy at 660°C-720°C, stirring, and then melting and casting to form an ingot, and adding 0.5-1.0% of a complex phase modifier during the casting; Step 2: feeding the ingot into an extruder for extrusion into an aluminum pipe, controlling the extrusion outlet, and composite the outer surface of the aluminum pipe with a 3-series aluminum alloy composited by a planetary rolling mill continuous casting and rolling method to form a base pipe; Step 3: brushing and grinding the outer surface of the base pipe for the inner composite layer to remove the oxide film, then inserting the base pipe and expanding the pipe to form a set tube blank; Step 4: using a planetary tube rolling mill to perform a single-pass rolling on the set tube blank, and completing the rolling to obtain a composite pipe. The aluminum-based composite pipe produced by the present invention can achieve a functional combination of various materials by changing the chemical composition of the metal between layers, and has the characteristics of corrosion resistance, self-contained brazing filler metal, and enhanced heat transfer function.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum-based composite pipes, and in particular to a method for manufacturing aluminum-based composite pipes. Background Art

[0002] Aluminum alloys, with their low density and excellent machinability, are widely used in the aviation, aerospace, automotive, and electronics industries. However, with the rapid development of modern industry, aluminum alloys are no longer able to meet the performance requirements of industrial development in many aspects. Combining aluminum with other materials to create aluminum-based composites is one of the most important ways to improve the comprehensive mechanical properties of aluminum alloys.

[0003] Existing aluminum-based composite pipes are added with carbon nanotubes to enhance heat transfer and conductivity. However, the addition of carbon nanotubes reduces the corrosion resistance of the product. For example, Chinese patent document CN103276322A discloses an in-situ grown carbon nanotube-reinforced aluminum-based brazing filler metal prepared from nickel nitrate hexahydrate and aluminum-based composite powder. The mass percentage of nickel nitrate hexahydrate and aluminum-based composite powder is 2% to 10%, and the aluminum-based composite powder is an aluminum-based brazing filler metal powder of Al-Si, Al-Si-Cu, or Al-Cu-Ag series, with a purity of 99% or more.

[0004] For example, CN106119587A discloses a method for preparing an aluminum-based composite material with an effective addition of carbon nanotubes, comprising the following steps: 1) preparing a carbon nanotube-aluminum-based composite powder: placing carbon nanotubes, aluminum powder, and a foaming agent in a certain proportion into a high-energy ball mill, mixing them uniformly, and cooling them to obtain a composite powder; 2) preparing a carbon nanotube-aluminum-based composite ingot: placing the composite powder obtained in step 1) into a vacuum hot pressing furnace for sintering and densification to obtain a composite ingot; 3) smelting: after the pure aluminum ingot is melted, the composite ingot obtained in step 2) is added at a certain temperature, and the mixture is stirred, kept warm, and cast to obtain the product, a carbon nanotube-aluminum-based composite material. The addition of carbon nanotubes enhances the thermal conductivity of the product, but reduces its corrosion resistance, and therefore requires optimization and coordination of the two properties.

[0005] Based on this, the present invention provides a method for manufacturing an aluminum-based composite pipe by improving the process and raw materials. Summary of the Invention

[0006] In view of the defects of the prior art, the purpose of the present invention is to provide a method for manufacturing an aluminum-based composite tube to solve the problems raised in the above background technology.

[0007] The present invention solves the technical problem by adopting the following technical solutions:

[0008] The present invention provides a method for manufacturing an aluminum-based composite tube, comprising the following steps:

[0009] Step 1: adding 1-5% of the total amount of the liquid aluminum alloy to the 7 series or 4 series liquid aluminum alloy at 660-720°C, stirring, and then melting and casting to form an ingot, and adding 0.5-1.0% of the complex phase modifier during the casting;

[0010] Step 2: The ingot is fed into an extruder for extrusion into an aluminum tube. The surface temperature of the extrusion outlet is controlled to be 480-550°C and the extrusion speed is 1-5m / min. The outer surface of the aluminum tube is composited with a 3 series aluminum alloy by continuous casting and rolling on a planetary rolling mill to form a base tube.

[0011] Step 3: After the outer surface of the base tube for the inner composite layer is brushed and polished to remove the oxide film, the base tube is inserted into the base tube and expanded to form a sleeve tube blank;

[0012] Step 4: Use a planetary tube rolling mill to perform single-pass rolling on the set tube blank, and after rolling is completed, a composite tube is obtained.

[0013] Preferably, the stirring speed in step 1 is 500-700 r / min, and the stirring time is 35-45 min.

[0014] Preferably, the preparation method of the homogeneous formulation is:

[0015] S1: placing the potassium hexatitanate whiskers at 100-120°C for a thermal reaction for 25-35 minutes, then raising the temperature to 185-195°C at a rate of 1-3°C / s, keeping the temperature for 5-10 minutes, and then air-cooling to room temperature to obtain thermally modified potassium hexatitanate whiskers;

[0016] S2: adding the heat-modified potassium hexatitanate whiskers into a uniform dispersion liquid for stirring and dispersion treatment, with a stirring temperature of 75-85°C, a stirring speed of 300-400 r / min, and a stirring time of 25-35 min. After the stirring is completed, washing with water and drying to obtain uniformly dispersed modified potassium hexatitanate whiskers;

[0017] S3: The uniformly dispersed modified potassium hexatitanate whiskers are sent into the corrosion-resistant silane liquid for stirring and dispersion treatment. The stirring temperature is 55-65°C, the stirring speed is 600-700r / min, and the stirring time is 45-55min. After the stirring is completed, the mixture is washed with water and dried to obtain a homogeneous formulation.

[0018] Preferably, the preparation method of the uniform dispersion is: 10-20 parts of hydrochloric acid solution, 1-5 parts of sodium alginate, 1-2 parts of strontium chloride and 15-25 parts of N,N-dimethylformamide are stirred and fully mixed to obtain the uniform dispersion.

[0019] Preferably, the mass fraction of the hydrochloric acid solution is 5-7%.

[0020] Preferably, the preparation method of the corrosion-resistant silane liquid is: add 5-10 parts of hexamethylene diisocyanate to 10-20 parts of acetone solvent, stir for 10-20 minutes, and the stirring speed is 100-200r / min, and then add 1-3 parts of N-2-aminoethyl-3-aminopropyltrimethoxysilane and 1-2 parts of rare earth cerium chloride, continue stirring at a speed of 350-450r / min for 10-20 minutes, and end the stirring to obtain the corrosion-resistant silane liquid.

[0021] Preferably, the rare earth cerium chloride is prepared by mixing rare earth cerium and hydrochloric acid in a weight ratio of 1:5.

[0022] Preferably, the preparation method of the multiphase modified material is:

[0023] 5-10 parts of chromium oxide are added to 10-20 parts of ethanol solvent, and then 1-2 parts of lanthanum maleate and 0.1-0.3 parts of nano-silicon dioxide are added, and ultrasonic treatment is performed. After the treatment is completed, the mixture is washed with water and dried to obtain a multiphase modified material.

[0024] Preferably, the ultrasonic power of the ultrasonic treatment is 500-700W, and the ultrasonic time is 25-35 minutes.

[0025] Preferably, during the rolling in step 4, the cross-sectional reduction rate is 50% to 90%, the rolling speed is 8 m / min to 12 m / min, and the temperature rise in the deformation zone is 300° C. to 500° C.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention relates to a method for manufacturing an aluminum-based composite pipe. The pipe structure after composite rolling is in a recrystallized state, and the layers are metallurgically bonded. The aluminum-based composite pipe can be produced with fewer steps, higher efficiency, and lower cost. The produced aluminum-based composite pipe can achieve functional combinations of various materials by changing the chemical composition of the metals between layers. The pipe has the characteristics of corrosion resistance, self-contained brazing filler metal, and enhanced heat transfer.

[0028] The present invention adds a homogeneous blending agent to the liquid aluminum alloy and simultaneously adds a complex phase modifier during casting, and the two cooperate to enhance the thermal conductivity and corrosion resistance of the product; the homogeneous blending agent uses potassium hexatitanate whiskers that are first subjected to a thermal improvement treatment, and then improved by a homogenizing liquid and a corrosion-resistant silane liquid. The whiskers after the thermal improvement treatment have high activity, and after being treated with a hydrochloric acid solution, sodium alginate, strontium chloride, and N,N-dimethylformyl in the homogenizing liquid, the dispersion is enhanced, and then after being improved and modified by N-2-aminoethyl-3-aminopropyltrimethoxysilane and rare earth cerium chloride in the corrosion-resistant silane liquid, the corrosion resistance of the product is improved;

[0029] The multiphase modified material uses chromium oxide as the base material, which can form an oxide film on the substrate. The addition of nano-silicon dioxide can enhance the density of the oxide film. At the same time, combined with lanthanum maleate, it further enhances the corrosion resistance of the product. After raw material improvement and process optimization, the corrosion resistance and thermal conductivity of the product can be improved in a coordinated manner. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] A method for manufacturing an aluminum-based composite tube according to this embodiment includes the following steps:

[0032] Step 1: adding 1-5% of the total amount of the liquid aluminum alloy to the 7 series or 4 series liquid aluminum alloy at 660-720°C, stirring, and then melting and casting to form an ingot, and adding 0.5-1.0% of the complex phase modifier during the casting;

[0033] Step 2: The ingot is fed into an extruder for extrusion into an aluminum tube. The surface temperature of the extrusion outlet is controlled to be 480-550°C and the extrusion speed is 1-5m / min. The outer surface of the aluminum tube is composited with a 3 series aluminum alloy by continuous casting and rolling on a planetary rolling mill to form a base tube.

[0034] Step 3: After the outer surface of the base tube for the inner composite layer is brushed and polished to remove the oxide film, the base tube is inserted into the base tube and expanded to form a sleeve tube blank;

[0035] Step 4: Use a planetary tube rolling mill to perform single-pass rolling on the set tube blank, and after rolling is completed, a composite tube is obtained.

[0036] In step 1 of this embodiment, the stirring speed is 500-700 r / min, and the stirring time is 35-45 min.

[0037] The preparation method of the homogeneous formulation of this embodiment is:

[0038] S1: placing the potassium hexatitanate whiskers at 100-120°C for a thermal reaction for 25-35 minutes, then raising the temperature to 185-195°C at a rate of 1-3°C / s, keeping the temperature for 5-10 minutes, and then air-cooling to room temperature to obtain thermally modified potassium hexatitanate whiskers;

[0039] S2: adding the heat-modified potassium hexatitanate whiskers into a uniform dispersion liquid for stirring and dispersion treatment, with a stirring temperature of 75-85°C, a stirring speed of 300-400 r / min, and a stirring time of 25-35 min. After the stirring is completed, washing with water and drying to obtain uniformly dispersed modified potassium hexatitanate whiskers;

[0040] S3: The uniformly dispersed modified potassium hexatitanate whiskers are sent into the corrosion-resistant silane liquid for stirring and dispersion treatment. The stirring temperature is 55-65°C, the stirring speed is 600-700r / min, and the stirring time is 45-55min. After the stirring is completed, the mixture is washed with water and dried to obtain a homogeneous formulation.

[0041] The preparation method of the uniform dispersion of this embodiment is as follows: 10-20 parts of hydrochloric acid solution, 1-5 parts of sodium alginate, 1-2 parts of strontium chloride and 15-25 parts of N,N-dimethylformamide are stirred and thoroughly mixed to obtain a uniform dispersion.

[0042] The mass fraction of the hydrochloric acid solution in this embodiment is 5-7%.

[0043] The preparation method of the corrosion-resistant silane liquid of this embodiment is as follows: 5-10 parts of hexamethylene diisocyanate are added to 10-20 parts of acetone solvent, stirred for 10-20 minutes at a stirring speed of 100-200 r / min, and then 1-3 parts of N-2-aminoethyl-3-aminopropyltrimethoxysilane and 1-2 parts of rare earth cerium chloride are added, and stirring is continued at a speed of 350-450 r / min for 10-20 minutes. After the stirring is completed, the corrosion-resistant silane liquid is obtained.

[0044] The rare earth cerium chloride of this embodiment is prepared by mixing rare earth cerium and hydrochloric acid in a weight ratio of 1:5.

[0045] The preparation method of the multiphase modified material of this embodiment is:

[0046] 5-10 parts of chromium oxide are added to 10-20 parts of ethanol solvent, and then 1-2 parts of lanthanum maleate and 0.1-0.3 parts of nano-silicon dioxide are added, and ultrasonic treatment is performed. After the treatment is completed, the mixture is washed with water and dried to obtain a multiphase modified material.

[0047] The ultrasonic power of the ultrasonic treatment in this embodiment is 500-700W, and the ultrasonic time is 25-35min.

[0048] In step 4 of this embodiment, during rolling, the cross-sectional reduction rate is 50% to 90%, the rolling speed is 8 m / min to 12 m / min, and the temperature rise in the deformation zone is 300° C. to 500° C.

[0049] Example 1.

[0050] A method for manufacturing an aluminum-based composite tube according to this embodiment includes the following steps:

[0051] Step 1: Add 1% of the total amount of the liquid aluminum alloy to the 7 series or 4 series liquid aluminum alloy at 660°C, stir, and then melt and cast to form an ingot, and add 0.5% of the complex phase modifier during the casting;

[0052] Step 2: The ingot is fed into an extruder for extrusion into an aluminum tube. The surface temperature of the extrusion outlet is controlled to be 480° C. and the extrusion speed is 1 m / min. The outer surface of the aluminum tube is composited with a 3 series aluminum alloy by continuous casting and rolling on a planetary rolling mill to form a base tube.

[0053] Step 3: After the outer surface of the base tube for the inner composite layer is brushed and polished to remove the oxide film, the base tube is inserted into the base tube and expanded to form a sleeve tube blank;

[0054] Step 4: Use a planetary tube rolling mill to perform single-pass rolling on the set tube blank, and after rolling is completed, a composite tube is obtained.

[0055] In step 1 of this embodiment, the stirring speed is 500 r / min and the stirring time is 35 min.

[0056] The preparation method of the homogeneous formulation of this embodiment is:

[0057] S1: The potassium hexatitanate whiskers were placed at 100°C for a thermal reaction for 25 min, then heated to 185°C at a rate of 1°C / s, kept at that temperature for 5 min, and then air-cooled to room temperature to obtain thermally modified potassium hexatitanate whiskers;

[0058] S2: adding the heat-modified potassium hexatitanate whiskers into the uniform dispersion liquid for stirring and dispersion treatment at a stirring temperature of 75°C, a stirring speed of 300 r / min, and a stirring time of 25 min. After the stirring is completed, washing with water and drying to obtain uniformly dispersed modified potassium hexatitanate whiskers;

[0059] S3: The uniformly dispersed modified potassium hexatitanate whiskers are sent into the corrosion-resistant silane liquid for stirring and dispersion treatment. The stirring temperature is 55°C, the stirring speed is 600r / min, and the stirring time is 45min. After the stirring is completed, the mixture is washed with water and dried to obtain a homogeneous formulation.

[0060] The preparation method of the uniform dispersion of this embodiment is as follows: 10 parts of hydrochloric acid solution, 1 part of sodium alginate, 1 part of strontium chloride and 1 part of N,N-dimethylformamide are stirred and mixed thoroughly to obtain the uniform dispersion.

[0061] The mass fraction of the hydrochloric acid solution in this embodiment is 5%.

[0062] The preparation method of the corrosion-resistant silane liquid of this embodiment is as follows: 5 parts of hexamethylene diisocyanate are added to 10 parts of acetone solvent, stirred for 10 minutes at a stirring speed of 100 r / min, and then 1 part of N-2-aminoethyl-3-aminopropyltrimethoxysilane and 1 part of rare earth cerium chloride are added, and stirring is continued at a speed of 350 r / min for 10 minutes. After the stirring is completed, the corrosion-resistant silane liquid is obtained.

[0063] The rare earth cerium chloride of this embodiment is prepared by mixing rare earth cerium and hydrochloric acid in a weight ratio of 1:5.

[0064] The preparation method of the multiphase modified material of this embodiment is:

[0065] 5 parts of chromium oxide are added to 10 parts of ethanol solvent, and then 1 part of lanthanum maleate and 0.1 part of nano-silicon dioxide are added, and ultrasonic treatment is performed. After the treatment is completed, the mixture is washed with water and dried to obtain a multiphase modified material.

[0066] The ultrasonic treatment in this embodiment has an ultrasonic power of 500 W and an ultrasonic time of 25 min.

[0067] In step 4 of this embodiment, the cross-sectional reduction rate during rolling is 50%, the rolling speed is 8 m / min to 12 m / min, and the temperature rise in the deformation zone is 300°C.

[0068] Example 2.

[0069] A method for manufacturing an aluminum-based composite tube according to this embodiment includes the following steps:

[0070] Step 1: Add 5% of the total amount of the liquid aluminum alloy to the 7 series or 4 series liquid aluminum alloy at 720°C, stir, and then melt and cast to form an ingot, and add 1.0% of the complex phase modifier during the casting;

[0071] Step 2: The ingot is fed into an extruder to be extruded into an aluminum tube. The surface temperature of the extrusion outlet is controlled to be 550° C. and the extrusion speed is 5 m / min. The outer surface of the aluminum tube is composited with a 3 series aluminum alloy by continuous casting and rolling on a planetary rolling mill to form a base tube.

[0072] Step 3: After the outer surface of the base tube for the inner composite layer is brushed and polished to remove the oxide film, the base tube is inserted into the base tube and expanded to form a sleeve tube blank;

[0073] Step 4: Use a planetary tube rolling mill to perform single-pass rolling on the set tube blank, and after rolling is completed, a composite tube is obtained.

[0074] In step 1 of this embodiment, the stirring speed is 700 r / min and the stirring time is 45 min.

[0075] The preparation method of the homogeneous formulation of this embodiment is:

[0076] S1: The potassium hexatitanate whiskers were placed at 120°C for a thermal reaction for 35 minutes, then heated to 195°C at a rate of 3°C / s, kept at that temperature for 10 minutes, and then air-cooled to room temperature to obtain thermally modified potassium hexatitanate whiskers;

[0077] S2: adding the heat-modified potassium hexatitanate whiskers into the uniform dispersion liquid for stirring and dispersion treatment at a stirring temperature of 85°C, a stirring speed of 400 r / min, and a stirring time of 35 min. After the stirring is completed, washing with water and drying to obtain uniformly dispersed modified potassium hexatitanate whiskers;

[0078] S3: The uniformly dispersed modified potassium hexatitanate whiskers are sent into the corrosion-resistant silane liquid for stirring and dispersion treatment. The stirring temperature is 65°C, the stirring speed is 700r / min, and the stirring time is 55min. After the stirring is completed, the mixture is washed with water and dried to obtain a homogeneous formulation.

[0079] The preparation method of the uniform dispersion of this embodiment is as follows: 20 parts of hydrochloric acid solution, 5 parts of sodium alginate, 2 parts of strontium chloride and 25 parts of N,N-dimethylformamide are stirred and thoroughly mixed to obtain a uniform dispersion.

[0080] The mass fraction of the hydrochloric acid solution in this embodiment is 7%.

[0081] The preparation method of the corrosion-resistant silane liquid of this embodiment is as follows: 10 parts of hexamethylene diisocyanate are added to 20 parts of acetone solvent, stirred for 20 minutes at a stirring speed of 200 r / min, and then 3 parts of N-2-aminoethyl-3-aminopropyltrimethoxysilane and 2 parts of rare earth cerium chloride are added, and stirring is continued at a speed of 450 r / min for 20 minutes. After the stirring is completed, the corrosion-resistant silane liquid is obtained.

[0082] The rare earth cerium chloride of this embodiment is prepared by mixing rare earth cerium and hydrochloric acid in a weight ratio of 1:5.

[0083] The preparation method of the multiphase modified material of this embodiment is:

[0084] 10 parts of chromium oxide are added to 20 parts of ethanol solvent, and then 2 parts of lanthanum maleate and 0.3 parts of nano-silicon dioxide are added, and ultrasonic treatment is performed. After the treatment is completed, the mixture is washed with water and dried to obtain a multiphase modified material.

[0085] The ultrasonic treatment in this embodiment has an ultrasonic power of 700 W and an ultrasonic time of 35 min.

[0086] In step 4 of this embodiment, the cross-sectional reduction rate during rolling is 90%, the rolling speed is 12 m / min, and the temperature rise in the deformation zone is 3500° C.

[0087] Example 3.

[0088] A method for manufacturing an aluminum-based composite tube according to this embodiment includes the following steps:

[0089] Step 1: Add 3% of the total amount of the liquid aluminum alloy to the 7 series or 4 series liquid aluminum alloy at 690°C, stir, and then melt and cast to form an ingot, and add 0.75% of the complex phase modifier during the casting;

[0090] Step 2: The ingot is fed into an extruder for extrusion into an aluminum tube. The surface temperature of the extrusion outlet is controlled to be 525° C. and the extrusion speed is 3 m / min. The outer surface of the aluminum tube is composited with a 3 series aluminum alloy by continuous casting and rolling on a planetary rolling mill to form a base tube.

[0091] Step 3: After the outer surface of the base tube for the inner composite layer is brushed and polished to remove the oxide film, the base tube is inserted into the base tube and expanded to form a sleeve tube blank;

[0092] Step 4: Use a planetary tube rolling mill to perform single-pass rolling on the set tube blank, and after rolling is completed, a composite tube is obtained.

[0093] In step 1 of this embodiment, the stirring speed is 600 r / min and the stirring time is 40 min.

[0094] The preparation method of the homogeneous formulation of this embodiment is:

[0095] S1: The potassium hexatitanate whiskers were placed at 110°C for a thermal reaction for 30 min, then heated to 190°C at a rate of 2°C / s, kept at that temperature for 7.5 min, and then air-cooled to room temperature to obtain thermally modified potassium hexatitanate whiskers;

[0096] S2: adding the heat-modified potassium hexatitanate whiskers into a uniform dispersion liquid for stirring and dispersion treatment at a stirring temperature of 80°C, a stirring speed of 350 r / min, and a stirring time of 30 min. After the stirring is completed, washing with water and drying to obtain uniformly dispersed modified potassium hexatitanate whiskers;

[0097] S3: The uniformly dispersed modified potassium hexatitanate whiskers are sent into the corrosion-resistant silane liquid for stirring and dispersion treatment. The stirring temperature is 60°C, the stirring speed is 650r / min, and the stirring time is 50min. After the stirring is completed, the mixture is washed with water and dried to obtain a homogeneous formulation.

[0098] The preparation method of the uniform dispersion of this embodiment is as follows: 15 parts of hydrochloric acid solution, 2 parts of sodium alginate, 1.5 parts of strontium chloride and 20 parts of N,N-dimethylformamide are stirred and thoroughly mixed to obtain a uniform dispersion.

[0099] The mass fraction of the hydrochloric acid solution in this embodiment is 6%.

[0100] The preparation method of the corrosion-resistant silane liquid of this embodiment is as follows: 7.5 parts of hexamethylene diisocyanate are added to 15 parts of acetone solvent, stirred for 15 minutes at a stirring speed of 150 r / min, and then 2 parts of N-2-aminoethyl-3-aminopropyltrimethoxysilane and 1.5 parts of rare earth cerium chloride are added, and stirring is continued at a speed of 400 r / min for 15 minutes. After the stirring is completed, the corrosion-resistant silane liquid is obtained.

[0101] The rare earth cerium chloride of this embodiment is prepared by mixing rare earth cerium and hydrochloric acid in a weight ratio of 1:5.

[0102] The preparation method of the multiphase modified material of this embodiment is:

[0103] 7.5 parts of chromium oxide were added to 15 parts of ethanol solvent, and then 1.5 parts of lanthanum maleate and 0.2 parts of nano-silicon dioxide were added, and ultrasonic treatment was performed. After the treatment was completed, the mixture was washed with water and dried to obtain a multiphase modified material.

[0104] The ultrasonic treatment in this embodiment has an ultrasonic power of 600 W and an ultrasonic time of 30 min.

[0105] In step 4 of this embodiment, the cross-sectional reduction rate during rolling is 75%, the rolling speed is 10 m / min, and the temperature rise in the deformation zone is 400°C.

[0106] Comparative Example 1.

[0107] The difference from Example 3 is that no homogeneous formulation agent is added.

[0108] Comparative Example 2.

[0109] The difference from Example 3 is that the potassium hexatitanate whiskers in the homogeneous formulation are replaced by carbon nanotubes.

[0110] Comparative Example 3.

[0111] The difference from Example 3 is that the potassium hexatitanate whiskers in the homogeneous formulation are silicon nitride whiskers.

[0112] Comparative Example 4.

[0113] The difference from Example 3 is that the preparation method of the dispersion is different:

[0114] 15 parts of citric acid, 2 parts of sodium citrate, 1.5 parts of cobalt chloride and 20 parts of N,N-dimethylformamide were stirred and mixed thoroughly to obtain a uniform dispersion.

[0115] Comparative Example 5.

[0116] The difference from Example 3 is that the preparation method of the corrosion-resistant silane liquid is different:

[0117] Add 7.5 parts of tetra-n-propyl zirconate to 15 parts of acetone solvent and stir for 15 minutes at a stirring speed of 150 r / min. Then add 2 parts of silane coupling agent KH560 and 1.5 parts of hydrochloric acid and continue stirring at a speed of 400 r / min for 15 minutes. After stirring, a corrosion-resistant silane liquid is obtained.

[0118] Comparative Example 6.

[0119] The difference from Example 3 is that no multiphase modifying material is added.

[0120] Comparative Example 7.

[0121] The difference from Example 3 is that maleic anhydride is used instead of lanthanum maleate in the preparation of the composite modified material;

[0122] The preparation method of the multiphase modified material is as follows:

[0123] 7.5 parts of chromium oxide were added to 15 parts of ethanol solvent, and then 1.5 parts of maleic anhydride and 0.2 parts of nano-silicon dioxide were added, and ultrasonic treatment was performed. After the treatment was completed, the mixture was washed with water and dried to obtain a multiphase modified material.

[0124] Comparative Example 8.

[0125] The difference from Example 3 is that no nano-silicon dioxide is added in the preparation of the multiphase modified material.

[0126] Using a salt spray tester, the pH is around 3.0-3.1, the saturator temperature is 40℃, and the test temperature is 34.3℃. The sample is tested for corrosion performance and the time it takes for surface corrosion to appear on the pipe surface. The thermal conductivity coefficient is measured according to the GB / T3651-2008 method. The test results are as follows:

[0127] The product performance tests of Examples 1-3 and Comparative Examples 1-8 are as follows:

[0128] Facial spot time (h) Thermal conductivity (W / (mk)) Example 1 3450 174 Example 2 3453 176 Example 3 3456 178 Comparative Example 1 3115 153 Comparative Example 2 2950 184 Comparative Example 3 3352 170 Comparative Example 4 3215 165 Comparative Example 5 3196 162 Comparative Example 6 3265 181 Comparative Example 7 3412 171 Comparative Example 8 3387 168

[0129] From Examples 1-3 and Comparative Examples 1-8, it can be seen that the surface spot time of Example 3 of the present invention can be as high as 3456 hours, and the thermal conductivity can reach 178W / (mk). From Comparative Example 2, it can be seen that the thermal conductivity can be increased to 184W / (mk) by replacing the homogeneous formulation with carbon nanotubes, but the surface spot time can be formed in 2950 hours, and the corrosion resistance is significantly reduced.

[0130] In Comparative Example 3, the potassium hexatitanate whiskers were replaced by silicon nitride whiskers, and the corrosion resistance and thermal conductivity were reduced. The selection of potassium hexatitanate whiskers has a special effect;

[0131] As can be seen from Comparative Examples 4-5, the performance of the products will decline when the preparation methods of the uniform dispersion liquid and the corrosion-resistant silane liquid are different. At the same time, when the preparation method of the corrosion-resistant silane liquid is changed, the corrosion resistance and thermal conductivity performance decline trend is more obvious.

[0132] It can be seen from Comparative Examples 6-8 that the addition of the multiphase modified material slightly affects the thermal conductivity, but significantly enhances the corrosion resistance of the product;

[0133] At the same time, the addition of lanthanum maleate in the multiphase modified material can play an important role in optimizing product performance; and the addition of nano-silicon dioxide can optimize the corrosion resistance and thermal conductivity of the product.

[0134] Experimental Example 2

[0135] The surface spot position of the product samples of Examples 1-3 and Comparative Examples 1-8 was repeatedly subjected to a 180° bending test for more than three times to test the fracture phenomenon and whether there was any corrosion liquid residue inside the fracture;

[0136] The test performance is as follows:

[0137]

[0138]

[0139] The product samples of Examples 1-3 did not break, while in Comparative Examples 1-8, except for the use of silicon nitride whiskers in the homogeneous formulation for potassium hexatitanate whiskers and maleic anhydride in the preparation of the complex phase modifier instead of lanthanum maleate, the rest broke; however, in Comparative Examples 3 and 7, the samples that did not break had residual corrosive liquid, indicating that the products were severely damaged by the corrosive liquid. Based on this, the product formulas and processes of Examples 1-3 of the present invention have excellent corrosion resistance.

[0140] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0141] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for manufacturing an aluminum-based composite tube, characterized in that: The following steps are involved: Step 1: adding 1-5% of the total amount of the liquid aluminum alloy to the 7 series or 4 series liquid aluminum alloy at 660-720°C, stirring, and then melting and casting to form an ingot, and adding 0.5-1.0% of the complex phase modifier during the casting; Step 2: The ingot is fed into an extruder for extrusion into an aluminum tube. The surface temperature of the extrusion outlet is controlled to be 480-550°C and the extrusion speed is 1-5m / min. The outer surface of the aluminum tube is composited with a 3 series aluminum alloy by continuous casting and rolling on a planetary rolling mill to form a base tube. Step 3: After the outer surface of the base tube for the inner composite layer is brushed and polished to remove the oxide film, the base tube is inserted into the base tube and expanded to form a sleeve tube blank; Step 4: Use a planetary tube rolling mill to perform single-pass rolling on the set tube blank, and after rolling is completed, a composite tube is obtained; The preparation method of the homogeneous formulation is: S1: placing the potassium hexatitanate whiskers at 100-120°C for a thermal reaction for 25-35 minutes, then raising the temperature to 185-195°C at a rate of 1-3°C / s, keeping the temperature for 5-10 minutes, and then air-cooling to room temperature to obtain thermally modified potassium hexatitanate whiskers; S2: adding the heat-modified potassium hexatitanate whiskers into a uniform dispersion liquid for stirring and dispersion treatment, with a stirring temperature of 75-85°C, a stirring speed of 300-400 r / min, and a stirring time of 25-35 min. After the stirring is completed, washing with water and drying to obtain uniformly dispersed modified potassium hexatitanate whiskers; S3: The uniformly dispersed modified potassium hexatitanate whiskers are fed into the corrosion-resistant silane solution for stirring and dispersion treatment at a stirring temperature of 55-65°C, a stirring speed of 600-700 r / min, and a stirring time of 45-55 min. After the stirring is completed, the mixture is washed with water and dried to obtain a homogeneous formulation; The preparation method of the multiphase modified material is: 5-10 parts of chromium oxide are added to 10-20 parts of ethanol solvent, and then 1-2 parts of lanthanum maleate and 0.1-0.3 parts of nano-silicon dioxide are added, and ultrasonic treatment is performed. After the treatment is completed, the mixture is washed with water and dried to obtain a multiphase modified material.

2. The method for manufacturing an aluminum-based composite tube according to claim 1, characterized in that: The stirring speed in the step 1 is 500-700 r / min, and the stirring time is 35-45 min.

3. The method for manufacturing an aluminum-based composite tube according to claim 1, characterized in that: The preparation method of the uniform dispersion is as follows: 10-20 parts of hydrochloric acid solution, 1-5 parts of sodium alginate, 1-2 parts of strontium chloride and 15-25 parts of N,N-dimethylformamide are stirred and fully mixed to obtain the uniform dispersion.

4. The method for manufacturing an aluminum-based composite tube according to claim 3, characterized in that: The mass fraction of the hydrochloric acid solution is 5-7%.

5. The method for manufacturing an aluminum-based composite tube according to claim 1, characterized in that: The preparation method of the corrosion-resistant silane liquid is as follows: 5-10 parts of hexamethylene diisocyanate are added to 10-20 parts of acetone solvent, stirred for 10-20 minutes at a stirring speed of 100-200 r / min, then 1-3 parts of N-2-aminoethyl-3-aminopropyltrimethoxysilane and 1-2 parts of rare earth cerium chloride are added, and stirring is continued at a speed of 350-450 r / min for 10-20 minutes. After the stirring is completed, the corrosion-resistant silane liquid is obtained.

6. The method for manufacturing an aluminum-based composite tube according to claim 5, characterized in that: The rare earth cerium chloride is prepared by mixing rare earth cerium and hydrochloric acid in a weight ratio of 1:

5.

7. The method for manufacturing an aluminum-based composite tube according to claim 1, characterized in that: The ultrasonic power of the ultrasonic treatment is 500-700W, and the ultrasonic time is 25-35 minutes.

8. The method for manufacturing an aluminum-based composite tube according to claim 1, characterized in that: During the rolling in step 4, the cross-sectional shrinkage is 50% to 90%, the rolling speed is 8m / min to 12m / min, and the temperature rise in the deformation zone is 300°C to 500°C.

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