A method for preparing a shielding net for a multi-point temperature sensor

Abstract

The present invention relates to a method for preparing a shielding net for a multi-point temperature sensor. The method adopts hydrogen pre-reduction, mixing and pressing, vacuum induction melting, high-temperature forging, rotary forging, wire drawing, shielding net weaving and other methods. The prepared shielding net has the advantages of high melting point, corrosion resistance, good strength at high temperature, high conductivity, suitable linear expansion coefficient and the like. The shielding net can be used in a photovoltaic diffusion furnace to resist high-temperature corrosion and shield electromagnetic interference. The purity, electromagnetic shielding efficiency and conductivity of the shielding net meet the performance requirements of the photovoltaic diffusion furnace for the material of the shielding net, which is of great significance to the application of temperature sensors.

Description

Technical Field

[0001] The patent of this invention belongs to the field of material processing and preparation, and particularly relates to a method for preparing a shielding net for a multi-point temperature sensor. Background Art

[0002] In recent years, the scale of photovoltaic diffusion furnace installation demand has continued to expand. In order to improve production efficiency, photovoltaic diffusion furnaces have been continuously expanded. The furnace body has the characteristics of high-power induction heating, long span of constant temperature zone (up to 4m), fast heating and cooling rate (20℃~30℃ / min), long-term high working temperature (1100℃~1200℃), and rich in strong corrosive media (boron, phosphorus). Since the alternating current of the furnace body generates an alternating magnetic field through the induction coil, the electromagnetic induction generated by the alternating magnetic field induces an alternating electromotive force in the temperature sensor measurement circuit, which generates a serious interference signal to the measurement of the temperature sensor, causing the measured temperature to fluctuate greatly or produce errors, resulting in over-temperature and under-temperature phenomena in the diffusion furnace, which seriously affects the efficient and stable production of photovoltaic diffusion furnaces.

[0003] Currently known shielding copper or aluminum meshes cannot be used in the field of photovoltaic temperature sensors due to the low melting points of copper and aluminum. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a shielding net for a temperature sensor in view of the deficiencies in the prior art. The shielding net prepared by the method of the present invention has the advantages of being resistant to high-temperature corrosion and can effectively shield the alternating electromotive force generated by electromagnetic induction in a large furnace body. The temperature sensor of the shielding net has the advantage of high temperature measurement accuracy and precise measurement.

[0005] The technical solution of the present invention is:

[0006] A method for preparing a shielding net for a temperature sensor comprises the following steps:

[0007] 1) Nickel powder hydrogen pre-reduction

[0008] Put high-purity nickel powder into a hydrogen reduction furnace, introduce high-purity hydrogen, the hydrogen flow rate is 4-8L / min, the reduction temperature is 350-450℃, the insulation time is 2-4h, and sieve;

[0009] The purpose of nickel powder reduction is to effectively remove the free oxygen in the nickel powder, reduce the influence of oxygen on the hot working brittleness of nickel metal, and reduce the oxygen content of nickel wire.

[0010] 2) Mixing and pressing

[0011] The reduced nickel powder, chromium powder and cobalt powder are put into an agate ball mill for high-energy ball milling, with a material-ball ratio of 1:0.3 and a ball milling time of 18 to 24 hours. The ball-milled powder is put into a die and pressed to obtain a cylindrical nickel billet;

[0012] The amount of the chromium powder and the cobalt powder is 0.05% to 0.10% of the total weight of the nickel powder, the chromium powder and the cobalt powder respectively;

[0013] The purpose of adding chromium powder is that chromium can enhance the high-temperature oxidation resistance and sulfidation performance of nickel, and improve the resistance of nickel wire to pitting and crevice corrosion; the purpose of adding cobalt powder is that cobalt can enhance the high-temperature strength of nickel and improve the resistance of nickel wire to carburization and sulfidation.

[0014] The purpose of using agate ball milling jars for high-energy ball milling is to ensure the uniformity of powder particle size, improve the powder forming ability, and evenly distribute chromium and cobalt elements in nickel powder.

[0015] 3) Vacuum induction melting

[0016] Put the cylindrical nickel billet into a vacuum melting furnace, evacuate the vacuum, gradually adjust the melting current from 0A to 30A until it is completely melted, and stir with electromagnetic force to form a nickel metal ingot;

[0017] The use of electromagnetic stirring and gradual adjustment of current during the smelting process can promote precise temperature control, while ensuring the uniform distribution of trace chromium and cobalt elements, which is conducive to the floating of impurities and reduces solidification shrinkage cavities in nickel ingots.

[0018] 4) High temperature forging

[0019] The nickel metal ingot is heated to 900°C to 1050°C for forging, and heat preservation is performed. The initial forging temperature is 1000°C to 1050°C, the final forging temperature is 700°C to 750°C, and the deformation amount of a single pass is 20% to 30% to obtain a nickel metal rod;

[0020] When forging nickel metal ingots, it is necessary to strike them quickly with a light hammer at the beginning. After a certain amount of deformation is achieved, the ingots should be struck quickly with a heavy hammer. At the same time, they are heated to the initial forging temperature to achieve homogenization annealing, which ensures the homogenization of the grain structure of the nickel ingots and avoids the generation of cracks on the surface of the nickel ingots.

[0021] 5) Rotary forging

[0022] The nickel metal rod is heated to a temperature of 700°C to 900°C, kept warm, and deformed by 15% to 20% in a single pass, and then rotary forged to obtain a nickel strip;

[0023] The nickel rod is processed by rotary forging, and the internal grains are further refined, which improves the uniformity of the grain structure.

[0024] 6) Wire drawing

[0025] Nickel strips are hot drawn at a temperature of 400°C to 550°C, with a single-pass deformation of 7% to 12%;

[0026] Before final drawing and sizing, high-precision diamond wire drawing dies are used for cold drawing. The deformation of a single cold drawing pass is 5% to 10%, and a nickel wire with a wire diameter of 0.1mm to 0.5mm ± 0.01mm is obtained. The nickel wire is washed with ultrasonic alkali to remove the lubricating oil attached to the surface of the nickel wire.

[0027] The nickel wire is subjected to hydrogen reduction annealing before cold drawing;

[0028] The wire drawing adopts the combined deformation processing method of hot drawing + cold drawing before final drawing and sizing, which is beneficial to improve the surface quality of the wire and reduce the number of intermediate annealing for stress relief during drawing. The high-precision diamond wire drawing die is used to improve the ovality of the drawn nickel wire, which can better control the uniformity of the ovality of the nickel wire.

[0029] 7) Shielding mesh weaving

[0030] The number of weaving spindles is 3 to 6, each spindle contains 1 to 3 nickel wires, the weaving pitch is 13 to 18 mm, the weaving angle is 30° to 45°, a layer of mesh structure is formed on the core, and the outer diameter of the weaving shielding net is φ4 to φ8 mm. Reasonable weaving angles and pitches can effectively improve the shielding efficiency of the shielding net.

[0031] The purity of the high-purity nickel powder is ≥99.95%, the Fisher particle size is 15-53μm, and the particle size is normally distributed; the purity of the high-purity chromium powder is ≥99.99%, the Fisher particle size is 5-25μm; the purity of the cobalt powder is ≥99.99%, the Fisher particle size is 5-25μm.

[0032] Step 1) The flow rate of the hydrogen is 4-8 L / min; the sieve opening is 120 mesh.

[0033] Step 2) The rotation speed of the ball mill is 90-150 r / min; the pressing pressure is 100 MPa-180 MPa, and the holding time is 15 s-30 s.

[0034] Step 3) Vacuum to 1×10 -3 Pa or above.

[0035] Step 3) The interval time of adjusting the current is 2 to 5 minutes; the stirring time is 2 to 5 minutes.

[0036] The heat preservation time of step 4) is 8 minutes to 15 minutes; the heat preservation time of step 5) is 5 minutes to 10 minutes.

[0037] Step 6) The lubricant for hot drawing is molybdenum disulfide; the lubricant for cold drawing is lubricating oil

[0038] Step 6) The annealing temperature of the hydrogen reduction annealing treatment is 650° C. to 750° C., and the holding time is 15 min to 20 min; the alkali solution is a NaOH solution with a concentration of 7 to 12%.

[0039] Step 7) The weaving line speed is 2-4 m / min.

[0040] The performance test of the method described in the present invention uses chemical analysis and inductively coupled plasma spectrometer to analyze the purity and trace element content of the shielding net. According to GB / T 26016-2010 high-purity nickel analysis: nickel purity ≥99.8%, chromium and cobalt mass fractions of 0.05% to 0.10%. The shielding effectiveness of the woven shielding net is tested according to GJB 6190-2008 electromagnetic shielding material shielding effectiveness measurement method. A signal generator, waveform generator, spectrum analyzer and transmission measurement device are used to detect and measure in the 100MHz to 2GHz frequency band. The electromagnetic shielding effectiveness is ≥30dB. The conductivity is tested according to GB / T 32791-2016 copper and copper alloy conductivity eddy current test method, using an eddy current conductivity meter device, and the conductivity of the shielding net is ≥90%IACS.

[0041] Beneficial effects of the present invention

[0042] The preparation method of the shielding net for multi-point temperature sensors described in this patent adopts hydrogen pre-reduction, mixing and pressing, vacuum induction melting, high-temperature forging, rotary forging, wire drawing, shielding net weaving and other technologies. The nickel wire used to prepare the shielding net has the advantages of high melting point, corrosion resistance, good strength at high temperature, high conductivity, and suitable linear expansion coefficient. It can be used in photovoltaic diffusion furnaces to resist high-temperature corrosion and shield electromagnetic interference. The purity, electromagnetic shielding effectiveness and conductivity of the shielding net meet the performance requirements of photovoltaic diffusion furnaces for the materials of the shielding net, which is of great significance to the application of temperature sensors.

[0043] (1) Hydrogen pre-reduction and high-energy ball milling were used. The free oxygen in the nickel powder was effectively removed, reducing the effect of oxygen on the hot working brittleness of nickel metal, and reducing the oxygen content of the nickel wire. The use of high-energy ball milling ensures the uniformity of the powder particle size, improves the powder forming ability, and evenly distributes chromium and cobalt elements in the cobalt powder. Chromium can enhance the high-temperature oxidation resistance and sulfidation performance of nickel, and improve the pitting and crevice corrosion resistance of nickel wire. Cobalt can enhance the high-temperature strength of nickel and improve the carbonization and sulfidation resistance of nickel wire.

[0044] (2) Vacuum induction melting has the advantage of using step-by-step current adjustment and electromagnetic stirring during the melting process, which promotes precise temperature control and ensures uniform distribution of chromium and cobalt elements, which is conducive to the floating of impurities and reduces solidification shrinkage cavities in nickel ingots.

[0045] (3) In the wire drawing process, a combined deformation processing method of hot drawing + cold drawing before final drawing and sizing is adopted, which is beneficial to improve the surface quality of the wire and reduce the number of intermediate annealing for stress relief during drawing. The high-precision diamond wire drawing die is used to improve the ovality of the drawn nickel wire, which can better control the uniformity of the ovality of the nickel wire.

[0046] (4) The applicant's experimental verification shows that the shielding net prepared by the method of the present invention has a purity of ≥99.8% of pure nickel according to GB / T 26016-2010, and the mass fraction of chromium and cobalt elements is 0.05% to 0.10%; according to GJB 6190-2008, the electromagnetic shielding effectiveness is ≥30dB at 100MHz to 2GHz; according to GB / T 32791-2016, the conductivity is ≥90%IACS, which can meet the performance requirements of photovoltaic diffusion furnaces for shielding net materials and can be used in the field of photovoltaic temperature sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the process of the present invention;

[0048] Figure 2 The shielding net is prepared by the present invention. DETAILED DESCRIPTION

[0049] Example 1: See Figure 1

[0050] Weigh 2 kg of high-purity nickel powder, load the high-purity nickel powder into a molybdenum boat and put it into a hydrogen reduction furnace, introduce high-purity hydrogen, the hydrogen flow rate is 6 L / min, the reduction temperature is 400°C, the insulation time is 3 h, and after the reduction is completed, pass through a 120-mesh sieve.

[0051] Use reduced nickel powder and add 0.10% chromium powder and 0.05% cobalt powder by mass fraction. Put the weighed nickel powder, chromium powder and cobalt powder into an agate ball mill for high-energy ball milling, with a material-ball ratio of 1:0.3, a ball milling time of 24h, and a speed of 130r / min. After the ball milling, put the powder into a die and press it into shape using a 500T hydraulic press, with a pressing pressure of 150MPa and a holding time of 30s. After demolding, a pressed cylindrical nickel billet is obtained.

[0052] The pressed cylindrical nickel billet was placed in a zirconia crucible and placed in a vacuum melting furnace. Argon gas was introduced into the furnace and then the vacuum was evacuated to 2.2×10 -3Pa, gradually adjust the smelting current from 0A to 30A, adjust the current interval to 5min, until it is completely melted, start electromagnetic stirring for 5min, and then guide the ingot into a nickel metal ingot with a diameter of φ50mm. Use a 200 kg air hammer for forging, the heating temperature is 1050℃, the holding time is 10min, the initial forging temperature is 1050℃, the final forging temperature is 700℃, and the single-pass deformation processing amount is 28%. Process the nickel metal ingot into a nickel metal bar of φ15mm.

[0053] The forged nickel rod is forged by rotary forging machine, with a single deformation amount of 18%, heating temperature of 900℃, and holding time of 10min. After rotary forging, a nickel bar with a diameter of φ5mm is obtained. The nickel bar is deformed by a combination of hot drawing + cold drawing before final drawing and sizing. The hot drawing temperature is 550℃, and the single drawing deformation amount is 12%. Cold drawing before final drawing and sizing, annealing temperature before cold drawing is 750℃, and the holding time is 20min. The single drawing deformation amount is 10%, and the final drawing diameter of the nickel wire is 0.5mm±0.01mm. The nickel wire is ultrasonically cleaned with an alkali solution NaOH concentration of 12% to remove the lubricating oil attached to the surface of the nickel wire.

[0054] The shielding net is woven by a horizontal braiding machine. There are 6 braiding spindles, 3 nickel wires in each spindle, a braiding pitch of 18mm, a braiding angle of 45°, and a braiding line speed of 4m / min. Through the cross-spiral winding of the nickel wire, a mesh structure is formed on the core. The outer diameter of the braided shielding net is φ8mm. See Figure 2 .

[0055] The purity and trace element content of the shielding net were analyzed according to GB / T 26016-2010 high-purity nickel analysis: nickel purity ≥ 99.90%, chromium mass fraction 0.092% and cobalt mass fraction 0.043%. The shielding effectiveness of the woven shielding net was tested according to GJB 6190-2008 electromagnetic shielding material shielding effectiveness measurement method, and the electromagnetic shielding effectiveness was 42dB in the 100MHz~2GHz frequency band. The conductivity was tested according to GB / T 32791-2016 copper and copper alloy conductivity eddy current test method, using an eddy current conductivity meter device, and the conductivity of the shielding net was 92.35%IACS. Example 2

[0056] Weigh 1.5kg of high-purity nickel powder, load the high-purity nickel powder into a molybdenum boat and put it into a hydrogen reduction furnace, pass high-purity hydrogen, the hydrogen flow rate is 5L / min, the reduction temperature is 350℃, the holding time is 3h, and after the reduction is completed, pass through a 120-mesh sieve. Use the reduced nickel powder and add 0.05% chromium powder and 0.10% cobalt powder by mass fraction. Put the weighed nickel powder, chromium powder and cobalt powder into an agate ball mill for high-energy ball milling, the material-ball ratio = 1:0.3, the ball milling time is 20h, and the speed is 120r / min. After the ball milling is completed, put the powder into a die and use a 500T hydraulic press to press and form it, the pressing pressure is 120MPa, the holding time is 20s, and the pressed cylindrical nickel billet is obtained after demolding.

[0057] The pressed cylindrical nickel billet was placed in a zirconia crucible and placed in a vacuum melting furnace. Argon gas was introduced into the furnace and then the vacuum was evacuated to 1.8×10 -3 Pa, gradually adjust the smelting current from 0A to 30A, adjust the current interval for 5min, until it is completely melted, start electromagnetic stirring for 5min, and then guide the ingot into a nickel metal ingot with a diameter of φ40mm. Use a 200 kg air hammer for forging, the heating temperature is 1020℃, the holding time is 8min, the initial forging temperature is 1020℃, the final forging temperature is 700℃, and the single-pass deformation processing amount is 25%. Process the nickel metal ingot into a nickel metal bar of φ14mm.

[0058] The forged nickel rod is forged by rotary forging machine, with a single deformation amount of 18%, heating temperature of 900℃, and holding time of 8min. After rotary forging, a nickel bar with a diameter of φ4mm is obtained. The nickel bar is deformed by a combination of hot drawing + cold drawing before final drawing and sizing. The hot drawing temperature is 500℃, and the single drawing deformation amount is 10%. Cold drawing before final drawing and sizing, annealing temperature before cold drawing is 700℃, and the holding time is 18min. The single drawing deformation amount is 8%, and the final drawing diameter of the nickel wire is 0.3mm±0.01mm. The nickel wire is ultrasonically cleaned with an alkali solution NaOH concentration of 10% to remove the lubricating oil attached to the surface of the nickel wire.

[0059] The shielding net is woven by a horizontal braiding machine, with 4 braiding spindles, 2 nickel wires in each spindle, a braiding pitch of 15mm, a braiding angle of 40°, and a braiding line speed of 3m / min. A mesh structure is formed on the core through the cross-spiral winding of the nickel wire. The outer diameter of the braided shielding net is φ6mm.

[0060] The purity and trace element content of the shielding net were analyzed according to GB / T 26016-2010 high-purity nickel analysis: nickel purity ≥ 99.92%, chromium mass fraction 0.042% and cobalt mass fraction 0.087%. The shielding effectiveness of the woven shielding net was tested according to GJB 6190-2008 electromagnetic shielding material shielding effectiveness measurement method, and the electromagnetic shielding effectiveness was 37dB in the 100MHz~2GHz frequency band. The conductivity was tested according to GB / T 32791-2016 copper and copper alloy conductivity eddy current test method, using an eddy current conductivity meter device, and the conductivity of the shielding net was 91.83%IACS. Example 3

[0061] Weigh 1.0kg of high-purity nickel powder, load the high-purity nickel powder into a molybdenum boat and put it into a hydrogen reduction furnace, pass high-purity hydrogen, the hydrogen flow rate is 4L / min, the reduction temperature is 350℃, the holding time is 2h, and after the reduction, pass through a 120-mesh sieve. Use the reduced nickel powder and add 0.10% chromium powder and 0.10% cobalt powder by mass fraction. Put the weighed nickel powder, chromium powder and cobalt powder into an agate ball mill for high-energy ball milling, the material-ball ratio = 1:0.3, the ball milling time is 18h, and the speed is 100r / min. After the ball milling, put the powder into a die and use a 500T hydraulic press to press and form it, the pressing pressure is 120MPa, the holding time is 15s, and the pressed cylindrical nickel billet is obtained after demolding.

[0062] The pressed cylindrical nickel billet was placed in a zirconia crucible and placed in a vacuum melting furnace. Argon gas was introduced into the furnace for cleaning and then the vacuum was evacuated to 2.0×10 -3 Pa, gradually adjust the smelting current from 0A to 30A, adjust the current interval for 3min, until it is completely melted, start electromagnetic stirring for 3min, and then guide the ingot into a nickel metal ingot with a diameter of φ30mm. Use a 200 kg air hammer for forging, the heating temperature is 1000℃, the holding time is 8min, the initial forging temperature is 1000℃, the final forging temperature is 700℃, and the single-pass deformation processing amount is 24%. Process the nickel metal ingot into a nickel metal bar of φ13mm.

[0063] The forged nickel rod is forged by rotary forging machine, with a single deformation amount of 15%, a heating temperature of 850℃, and a holding time of 8min. After rotary forging, a nickel bar with a diameter of φ3mm is obtained. The nickel bar is deformed by a combination of hot drawing + cold drawing before final drawing and sizing. The hot drawing temperature is 400℃, and the single drawing deformation amount is 8%. Cold drawing before final drawing and sizing, annealing temperature before cold drawing is 650℃, and the holding time is 15min. The single drawing deformation amount is 6%, and the final drawing diameter of the nickel wire is 0.1mm±0.01mm. The nickel wire is ultrasonically cleaned with an alkali solution NaOH concentration of 8% to remove the lubricating oil attached to the surface of the nickel wire.

[0064] The shielding net is woven by a horizontal braiding machine with 3 braiding spindles, 13 nickel wires in each spindle, a braiding pitch of 13mm, a braiding angle of 30°, and a braiding line speed of 2m / min. A mesh structure is formed on the core through the cross-spiral winding of the nickel wire. The outer diameter of the braided shielding net is φ4mm.

[0065] The purity and trace element content of the shielding net were analyzed according to GB / T 26016-2010 high-purity nickel analysis: nickel purity ≥ 99.92%, chromium mass fraction 0.089% and cobalt mass fraction 0.093%. The shielding effectiveness of the woven shielding net was tested according to GJB 6190-2008 electromagnetic shielding material shielding effectiveness measurement method, and the electromagnetic shielding effectiveness was 32dB in the 100MHz~2GHz frequency band. The conductivity was tested according to GB / T 32791-2016 copper and copper alloy conductivity eddy current test method, using an eddy current conductivity meter device, and the conductivity of the shielding net was 90.75%IACS.

Claims

1. A method for preparing a shielding net for a multi-point temperature sensor, characterized in that: The following steps are involved: 1) Nickel powder hydrogen pre-reduction Put high-purity nickel powder into a hydrogen reduction furnace, introduce high-purity hydrogen, the hydrogen flow rate is 4-8L / min, the reduction temperature is 350-450℃, the insulation time is 2-4h, and sieve; 2) Mixing and pressing The reduced nickel powder, chromium powder and cobalt powder are put into a ball mill for high-energy ball milling, with a material-ball ratio of 1:0.3 and a ball milling time of 18 to 24 hours. The ball-milled powder is put into a die and pressed to obtain a cylindrical nickel billet; The amount of the chromium powder and the cobalt powder is 0.05% to 0.10% of the total weight of the nickel powder, the chromium powder and the cobalt powder respectively; 3) Vacuum induction melting Put the cylindrical nickel billet into a vacuum melting furnace, evacuate the vacuum, gradually adjust the melting current from 0A to 30A until it is completely melted, stir, and ingotize into a nickel metal ingot; 4) High temperature forging The nickel metal ingot is heated to 900°C to 1050°C for forging, and heat preservation is performed. The initial forging temperature is 1000°C to 1050°C, the final forging temperature is 700°C to 750°C, and the deformation amount of a single pass is 20% to 30% to obtain a nickel metal rod; 5) Rotary forging The nickel metal rod is heated to a temperature of 700°C to 900°C, kept warm, and deformed by 15% to 20% in a single pass, and then rotary forged to obtain a nickel strip; 6) Wire drawing Nickel strips are hot drawn at a temperature of 400°C to 550°C, with a single-pass deformation of 7% to 12%; Before final drawing and sizing, high-precision diamond wire drawing dies are used for cold drawing. The deformation of a single cold drawing pass is 5% to 10%, and a nickel wire with a wire diameter of 0.1mm to 0.5mm ± 0.01mm is obtained. The nickel wire is washed with ultrasonic alkali. The nickel wire is subjected to hydrogen reduction annealing before cold drawing; 7) Shielding mesh weaving The number of braiding spindles is 3 to 6, each spindle contains 1 to 3 nickel wires, the braiding pitch is 13 to 18 mm, the braiding angle is 30° to 45°, and a mesh structure is formed on the core body. The outer diameter of the braided shielding net is φ4 to φ8 mm.

2. The preparation method according to claim 1, characterized in that: The purity of the high-purity nickel powder is ≥99.95%, the Fisher particle size is 15-53μm, and the particle size is normally distributed; the purity of the high-purity chromium powder is ≥99.99%, the Fisher particle size is 5-25μm; the purity of the cobalt powder is ≥99.99%, the Fisher particle size is 5-25μm.

3. The preparation method according to claim 1, characterized in that: Step 1) The flow rate of the hydrogen is 4-8 L / min; the sieve opening is 120 mesh.

4. The preparation method according to claim 1, characterized in that: Step 2) The rotation speed of the ball mill is 90-150 r / min; The pressing pressure is 100 MPa to 180 MPa, and the holding time is 15 s to 30 s.

5. The preparation method according to claim 1, characterized in that: Step 3) Vacuum to 1×10 -3 Pa or above.

6. The preparation method according to claim 1, characterized in that: Step 3) The interval time for adjusting the smelting current is 2 to 5 minutes; the stirring time is 2 to 5 minutes.

7. The preparation method according to claim 1, characterized in that: The heat preservation time of step 4) is 8 minutes to 15 minutes; the heat preservation time of step 5) is 5 minutes to 10 minutes.

8. The preparation method according to claim 1, characterized in that: Step 6) The lubricant for hot drawing is molybdenum disulfide; the lubricant for cold drawing is lubricating oil.

9. The preparation method according to claim 1, characterized in that: Step 6) The annealing temperature of the hydrogen reduction annealing treatment is 650° C. to 750° C., and the holding time is 15 min to 20 min. The alkali solution is a NaOH solution with a concentration of 7 to 12%.

10. The preparation method according to claim 1, characterized in that: Step 7) The weaving line speed is 2-4 m / min.

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