A high-temperature resistant loudspeaker voice coil wire and its preparation method

Abstract

This invention relates to the field of loudspeaker voice coil technology, specifically to a high-temperature resistant loudspeaker voice coil and its preparation method. It utilizes highly conductive graphene-based supercopper, comprising the following components in percentage: 1.2-1.5% graphene, 0.4-0.6% nano-silicon carbide, 0.08-0.17% rare earth oxide powder, 0.3-0.5% aluminum nitride whiskers, with the balance being high-purity oxygen-free copper and impurities, the total impurity content being less than 0.1%. Through multi-phase synergistic effects, its composition exhibits higher conductivity, better heat dissipation and high-temperature resistance, slower resistance rise and temperature increase under the same energy, and lower bending resistance and high-voltage leakage current, thus facilitating continuous operation of the voice coil.

Description

Technical Field

[0001] This invention relates to the field of loudspeaker voice coil technology, specifically to a high-temperature resistant loudspeaker voice coil and its preparation method. Background Technology

[0002] The voice coil is a coil assembly in an electrodynamic loudspeaker that generates mechanical vibration by cutting magnetic lines of force with an electric current; it is often referred to as the "heart of the loudspeaker." Its performance directly affects the loudspeaker's sound intensity characteristics, impedance curve, lifespan, and power handling. It consists of a frame, voice coil wire, reinforcing paper, and nylon wire. Common loudspeaker damage often stems from voice coil failure.

[0003] Ordinary voice coil wires are mostly composed of oxygen-free copper wires coated with insulating varnish. They heat up quickly and have poor heat dissipation, bending resistance, high voltage resistance, and low leakage current. Under long-term high-temperature operation, they are prone to carbonization and brittle breakage, leading to short circuits or open circuits, which affects the normal use of the speaker. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a high-temperature resistant loudspeaker voice coil wire.

[0005] Another objective of this invention is to provide a method for preparing high-temperature resistant loudspeaker voice coil wire. This method is simple to operate, easy to control, has high production efficiency, low production cost, and can be used for large-scale production.

[0006] The objective of this invention is achieved through the following technical solution: a high-temperature resistant loudspeaker voice coil wire, comprising a conductive core and an insulating varnish film covering the conductive core, wherein the conductive core is graphene-copper alloy and the conductivity of the conductive core is 102-118% IACS.

[0007] The high-temperature resistant speaker voice coil wire of the present invention uses graphene super copper with high conductivity. Its composition has a higher conductivity and better heat dissipation and high temperature resistance through multi-phase synergy. Under the same energy, the resistance rises more slowly and the temperature rises more slowly. It also has lower bending resistance and high voltage leakage current, which is more conducive to the continuous operation of the voice coil wire.

[0008] Preferably, the graphene-modified copper comprises the following components in percentage: 1.2-1.5% graphene, 0.4-0.6% nano-silicon carbide, 0.08-0.17% rare earth oxide powder, 0.3-0.5% aluminum nitride whiskers, with the balance being high-purity oxygen-free copper and impurities, the total amount of impurities being less than 0.1%.

[0009] Using the above technical solution, high-purity oxygen-free copper is used as the substrate to provide basic conductivity and mechanical strength, reducing the obstruction of electron migration by impurities. The added graphene, as a reinforcing phase, forms a three-dimensional conductive network with copper through its ultra-high carrier mobility, significantly improving conductivity and thermal conductivity. Simultaneously, the flexibility of graphene enhances fatigue resistance. The added nano-silicon carbide, as a nanograin boundary strengthener, helps refine copper grains (through the pinning grain boundary effect), reducing the grain size from 50-100 μm in traditional copper to 1-3 μm. The addition of rare earth oxide powder acts as an interface optimizer, forming chemical bonds (such as Sc-C bonds) at the copper-graphene interface, reducing interface resistance. At the same time, rare earth oxides can adsorb oxygen impurities in the copper matrix, reducing leakage current. The addition of aluminum nitride whiskers acts as a thermally conductive reinforcing phase, forming a synergistic thermally conductive network with graphene. The in-plane thermal conductivity of AlN (320 W / (m·K)) can fill the thermal conductivity gap between graphene layers, thereby increasing the overall thermal conductivity coefficient to 460-600 W / (m·K), making its heat dissipation and high-temperature resistance better.

[0010] Preferably, the rare earth oxide powder is a mixture of scandium oxide powder and erbium oxide powder in a weight ratio of 5-10:3-7; the graphene has a thickness of <0.34nm and has 1-3 layers.

[0011] Preferably, the method for preparing the graphene-based super copper includes the following steps: (S1) According to the weight percentage, graphene, nano silicon carbide and aluminum nitride whiskers are added to anhydrous ethanol for impregnation, then 0.8wt% PVP dispersant is added and ultrasonically broken for 2-3 hours, and then centrifuged at 5000-8000rpm for 10-20 minutes to remove undispersed large particles to obtain a suspension. (S2) Add rare earth oxide powder, high-purity oxygen-free copper, suspension and 0.3wt% stearic acid into a ball mill jar, ball-to-material ratio 15:1, speed 600-800rpm, ball mill for 10-12h to form a uniform composite. (S3) The composite is subjected to spark plasma sintering to obtain a dense bulk body; (S4) The dense block is heated to 800℃ and hot rolled in multiple passes using a four-roll mill. The reduction per pass is ≤15% and the total deformation is >80%, to obtain a plate blank with a thickness of 0.5mm. (S5) Cold roll the sheet blank to the target diameter, with a single pass reduction of ≤5% and a total deformation of 20%, to obtain a monofilament prototype; (S6) Using a diamond drawing die, the cold-rolled wire is drawn through multiple passes with a total deformation of >80%, gradually reducing the diameter to the target size. Then, it is heated to 350℃, held for 1.5 hours, and then air-cooled at a rate of ≤50℃ / min.

[0012] In step (S1), the ultrasonic crushing uses a power of 500W and a frequency of 25kHz, with a pulse mode of 5 seconds on and 2 seconds off to facilitate the formation of a uniform suspension. In step (S2), ball milling is used to uniformly embed nanoparticles into the surface of copper powder to form a composite. In steps (S3)-(S6), while maintaining high density, dynamic recovery softens the material to eliminate sintering internal stress and simultaneously form a preliminary fibrous structure (graphene oriented along the rolling direction); cold rolling introduces high-density dislocations (density > 10). 14 m -2 The process involves the formation of dislocation entanglements and cellular structures, significantly improving fatigue resistance. During the drawing process, graphene fibers are highly oriented along the axial direction, forming a composite structure of "copper matrix + graphene fibers," which effectively improves conductivity and synergistically enhances fatigue resistance, thereby improving bending resistance. In step (S6), the annealing temperature and time are controlled to eliminate internal stress and maintain high conductivity and thermal conductivity. Air cooling at a rate of ≤50℃ / min helps prevent surface cracks caused by thermal stress.

[0013] Preferably, the discharge plasma sintering treatment method in step (S3) involves loading the composite into a graphite mold and then placing it into an SPS sintering furnace. The furnace is evacuated to 10⁻⁴ Pa to prevent oxidation. The temperature is then increased to 900°C at a rate of 150°C / min, while a pressure of 80 MPa is applied simultaneously. The temperature is held for 8 minutes, and then cooled to room temperature at a rate of >80°C / min. The resulting dense bulk material has a relative density >99.5%.

[0014] By adopting the above technical solution, the interfacial bonding strength is improved through the synergistic effect of rapid heating, high pressure and pulsed current assistance, the surface oxide layer is broken and atomic diffusion is promoted, and the sintering activation energy is reduced. This can significantly improve the densification degree of the composite material, with a porosity of less than 0.5%, which can limit the grain size to the submicron level and improve the uniformity of the microstructure.

[0015] Preferably, in step (S6), the diamond drawing die contains a 5wt% nano-graphite suspension lubricant, the die cone angle is 12°, the length-to-diameter ratio of the lubrication zone is ≥3, and the drawing speed is controlled at 0.5-1m / s.

[0016] Using the above technical solution, the nano-graphite suspension forms a self-healing lubricating film during the drawing process, reducing mold wear and ensuring that the surface roughness Ra of the single filament is less than 0.1 μm.

[0017] Preferably, the heat resistance rating of the insulating varnish film reaches 220°C or higher, and the insulating varnish of the insulating varnish film is selected from Tritherm. A 981-M TAN or Tritherm A981-H is a polyamide-imide varnish with a heat resistance rating of 220 or higher, which greatly helps to improve thermal diffusion and performance under high voltage.

[0018] Preferably, the outer diameter of the conductive wire core is 0.04mm-0.5mm, and the thickness of the insulating varnish film is 0.02-0.03mm.

[0019] Another objective of the present invention is achieved through the following technical solution: the above-mentioned method for preparing high-temperature resistant loudspeaker voice coil wire includes the following steps: after the conductive wire core is soaked in acetone, ultrasonically cleaned and dried, an insulating varnish is applied using a four-coat four-bake process with the coating speed controlled at 5-20 m / min, and each time it is cured in a stepped high-temperature curing manner to obtain the high-temperature resistant loudspeaker voice coil wire.

[0020] Preferably, the stepped high-temperature curing method is as follows: First stage: 120℃, pre-curing for 2 minutes; Second stage: 200℃, curing for 2 minutes; Third stage: 300℃, final curing for 2 minutes. In the first stage, the solvent in the insulating varnish evaporates; in the second stage, the resin in the insulating varnish begins to soften and flow, filling micropores; in the third stage, the resin reacts to form a dense insulating varnish film, producing a voice coil wire with high insulation performance, heat resistance, and mechanical strength, meeting the long-term stable operation requirements of the speaker voice coil under high-frequency vibration and high-temperature environments.

[0021] The beneficial effects of the present invention are as follows: The high-temperature resistant speaker voice coil wire of the present invention adopts graphene super copper with high conductivity. Its composition has higher conductivity and better heat dissipation and high temperature resistance through multi-phase synergy. Under the same energy, the resistance rises more slowly and the temperature rises more slowly. It also has lower bending resistance and high voltage leakage current, which is more conducive to the continuous operation of the voice coil wire.

[0022] The preparation method of the present invention is simple to operate, easy to control, has high production efficiency, low production cost, and can be used for large-scale production. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the test fixture used in this invention to test the temperature rise; Figure 2 This is a schematic diagram of the micro resistance meter used for testing resistance in this invention; Figure 3 This is a schematic diagram of the test results for the high-voltage leakage current of the voice coil wire in Example 1; Figure 4This is a schematic diagram showing the test results of the high-voltage leakage current of the voice coil wire in Comparative Example 1. Detailed Implementation

[0024] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0025] Example 1 A high-temperature resistant loudspeaker voice coil wire includes a conductive core and an insulating varnish film covering the conductive core, wherein the conductive core is graphene-copper alloy.

[0026] The graphene-modified copper comprises the following components in percentage: 1.3% graphene, 0.5% nano-silicon carbide, 0.12% rare earth oxide powder, 0.4% aluminum nitride whiskers, with the balance being high-purity oxygen-free copper and impurities, the total amount of impurities being less than 0.1%.

[0027] The rare earth oxide powder is a mixture of scandium oxide powder and erbium oxide powder in a weight ratio of 8:5; the graphene has a thickness of 0.30 nm and has 2 layers.

[0028] The preparation method of the graphene-based super copper includes the following steps: (S1) According to the weight percentage, graphene, nano silicon carbide and aluminum nitride whiskers were added to anhydrous ethanol for impregnation, and then 0.8wt% PVP dispersant was added and ultrasonically broken for 3h. Then, the undispersed large particles were removed by centrifugation at 8000rpm for 15min to obtain a suspension. (S2) Rare earth oxide powder, high-purity oxygen-free copper, suspension and 0.3wt% stearic acid are added to a ball mill jar with a ball-to-material ratio of 15:1 and a rotation speed of 800 rpm for 12 hours to form a uniform composite. (S3) The composite is subjected to spark plasma sintering to obtain a dense bulk body; (S4) The dense block is heated to 800℃ and hot rolled in multiple passes using a four-roll mill. The reduction per pass is ≤15% and the total deformation is >80%, to obtain a plate blank with a thickness of 0.5mm. (S5) Cold roll the sheet blank to the target diameter, with a single pass reduction of ≤5% and a total deformation of 20%, to obtain a monofilament prototype; (S6) Using a diamond drawing die, the cold-rolled wire is drawn through multiple passes with a total deformation of >80%, gradually reducing the diameter to the target size. Then, it is heated to 350°C, held for 1.5 hours, and then air-cooled at a rate of 50°C / min.

[0029] The discharge plasma sintering process in step (S3) involves loading the composite into a graphite mold and then placing it into an SPS sintering furnace. The furnace is evacuated to 10⁻⁴ Pa to prevent oxidation. The temperature is then increased to 900°C at a rate of 150°C / min, while a pressure of 80 MPa is applied simultaneously. The temperature is held for 8 minutes, and then cooled to room temperature at a rate of 90°C / min. The resulting dense bulk material has a relative density >99.5%.

[0030] In step (S6), the diamond drawing die contains a 5wt% nano-graphite suspension lubricant, the die cone angle is 12°, the length-to-diameter ratio of the lubrication zone is 3.5, and the drawing speed is controlled at 0.7m / s.

[0031] The insulating varnish of the insulating film is selected from Tritherm. A 981-M TAN.

[0032] The outer diameter of the conductive wire core is 0.2 mm, and the thickness of the insulating varnish film is 0.025 mm.

[0033] The method for preparing the high-temperature resistant speaker voice coil wire includes the following steps: after soaking the conductive wire core in acetone, ultrasonically cleaning and drying, an insulating varnish is applied using a four-coat, four-bake process with the coating speed controlled at 10m / min, and each coating is cured using a stepped high-temperature curing method to obtain the high-temperature resistant speaker voice coil wire.

[0034] The stepped high-temperature curing method is as follows: first stage: 120℃, pre-curing for 2 minutes; second stage: 200℃, curing for 2 minutes; third stage: 300℃, final curing for 2 minutes.

[0035] Example 2 A high-temperature resistant loudspeaker voice coil wire includes a conductive core and an insulating varnish film covering the conductive core, wherein the conductive core is graphene-copper alloy.

[0036] The graphene-modified copper comprises the following components in percentage: 1.2% graphene, 0.4% nano-silicon carbide, 0.08% rare earth oxide powder, 0.3% aluminum nitride whiskers, with the balance being high-purity oxygen-free copper and impurities, the total amount of impurities being less than 0.1%.

[0037] The rare earth oxide powder is a mixture of scandium oxide powder and erbium oxide powder in a weight ratio of 5:3; the graphene has a thickness of 0.30 nm and a layer count of 1.

[0038] The preparation method of the graphene-based super copper includes the following steps: (S1) According to the weight percentage, graphene, nano silicon carbide and aluminum nitride whiskers were added to anhydrous ethanol for impregnation, and then 0.8wt% PVP dispersant was added and ultrasonically broken for 3h. Then, the undispersed large particles were removed by centrifugation at 8000rpm for 15min to obtain a suspension. (S2) Rare earth oxide powder, high-purity oxygen-free copper, suspension and 0.3wt% stearic acid are added to a ball mill jar with a ball-to-material ratio of 15:1 and a rotation speed of 800 rpm for 12 hours to form a uniform composite. (S3) The composite is subjected to spark plasma sintering to obtain a dense bulk body; (S4) The dense block is heated to 800℃ and hot rolled in multiple passes using a four-roll mill. The reduction per pass is ≤15% and the total deformation is >80%, to obtain a plate blank with a thickness of 0.5mm. (S5) Cold roll the sheet blank to the target diameter, with a single pass reduction of ≤5% and a total deformation of 20%, to obtain a monofilament prototype; (S6) Using a diamond drawing die, the cold-rolled wire is drawn through multiple passes with a total deformation of >80%, gradually reducing the diameter to the target size. Then, it is heated to 350°C, held for 1.5 hours, and then air-cooled at a rate of 50°C / min.

[0039] The discharge plasma sintering process in step (S3) involves loading the composite into a graphite mold and then placing it into an SPS sintering furnace. The furnace is evacuated to 10⁻⁴ Pa to prevent oxidation. The temperature is then increased to 900°C at a rate of 150°C / min, while a pressure of 80 MPa is applied simultaneously. The temperature is held for 8 minutes, and then cooled to room temperature at a rate of 90°C / min. The resulting dense bulk material has a relative density >99.5%.

[0040] In step (S6), the diamond drawing die contains a 5wt% nano-graphite suspension lubricant, the die cone angle is 12°, the length-to-diameter ratio of the lubrication zone is 3.5, and the drawing speed is controlled at 0.7m / s.

[0041] The insulating varnish of the insulating film is selected from Tritherm. A 981-M TAN.

[0042] The outer diameter of the conductive wire core is 0.1 mm, and the thickness of the insulating varnish film is 0.02 mm.

[0043] The method for preparing the high-temperature resistant speaker voice coil wire includes the following steps: after soaking the conductive wire core in acetone, ultrasonically cleaning and drying, an insulating varnish is applied using a four-coat, four-bake process with the coating speed controlled at 20m / min, and each coating is cured using a stepped high-temperature curing method to obtain the high-temperature resistant speaker voice coil wire.

[0044] The stepped high-temperature curing method is as follows: first stage: 120℃, pre-curing for 2 minutes; second stage: 200℃, curing for 2 minutes; third stage: 300℃, final curing for 2 minutes.

[0045] Example 3 A high-temperature resistant loudspeaker voice coil wire includes a conductive core and an insulating varnish film covering the conductive core, wherein the conductive core is graphene-copper alloy.

[0046] The graphene-modified copper comprises the following components in percentage: 1.5% graphene, 0.6% nano-silicon carbide, 0.17% rare earth oxide powder, 0.5% aluminum nitride whiskers, with the balance being high-purity oxygen-free copper and impurities, the total amount of impurities being less than 0.1%.

[0047] The rare earth oxide powder is a mixture of scandium oxide powder and erbium oxide powder in a weight ratio of 10:7; the graphene has a thickness of 0.30 nm and has 3 layers.

[0048] The preparation method of the graphene-based super copper includes the following steps: (S1) According to the weight percentage, graphene, nano silicon carbide and aluminum nitride whiskers were added to anhydrous ethanol for impregnation, and then 0.8wt% PVP dispersant was added and ultrasonically broken for 3h. Then, the undispersed large particles were removed by centrifugation at 8000rpm for 15min to obtain a suspension. (S2) Rare earth oxide powder, high-purity oxygen-free copper, suspension and 0.3wt% stearic acid are added to a ball mill jar with a ball-to-material ratio of 15:1 and a rotation speed of 800 rpm for 12 hours to form a uniform composite. (S3) The composite is subjected to spark plasma sintering to obtain a dense bulk body; (S4) The dense block is heated to 800℃ and hot rolled in multiple passes using a four-roll mill. The reduction per pass is ≤15% and the total deformation is >80%, to obtain a plate blank with a thickness of 0.5mm. (S5) Cold roll the sheet blank to the target diameter, with a single pass reduction of ≤5% and a total deformation of 20%, to obtain a monofilament prototype; (S6) Using a diamond drawing die, the cold-rolled wire is drawn through multiple passes with a total deformation of >80%, gradually reducing the diameter to the target size. Then, it is heated to 350°C, held for 1.5 hours, and then air-cooled at a rate of 50°C / min.

[0049] The discharge plasma sintering process in step (S3) involves loading the composite into a graphite mold and then placing it into an SPS sintering furnace. The furnace is evacuated to 10⁻⁴ Pa to prevent oxidation. The temperature is then increased to 900°C at a rate of 150°C / min, while a pressure of 80 MPa is applied simultaneously. The temperature is held for 8 minutes, and then cooled to room temperature at a rate of 90°C / min. The resulting dense bulk material has a relative density >99.5%.

[0050] In step (S6), the diamond drawing die contains a 5wt% nano-graphite suspension lubricant, the die cone angle is 12°, the length-to-diameter ratio of the lubrication zone is 3.5, and the drawing speed is controlled at 0.7m / s.

[0051] The insulating varnish of the insulating film is selected from Tritherm. A 981-M TAN.

[0052] The outer diameter of the conductive wire core is 0.5 mm, and the thickness of the insulating varnish film is 0.03 mm.

[0053] The method for preparing the high-temperature resistant speaker voice coil wire includes the following steps: after soaking the conductive wire core in acetone, ultrasonically cleaning and drying, an insulating varnish is applied using a four-coat, four-bake process with the coating speed controlled at 5m / min, and each coating is cured using a stepped high-temperature curing method to obtain the high-temperature resistant speaker voice coil wire.

[0054] The stepped high-temperature curing method is as follows: first stage: 120℃, pre-curing for 2 minutes; second stage: 200℃, curing for 2 minutes; third stage: 300℃, final curing for 2 minutes.

[0055] Example 4 A high-temperature resistant loudspeaker voice coil wire includes a conductive core and an insulating varnish film covering the conductive core, wherein the conductive core is graphene-copper alloy.

[0056] The graphene-modified copper comprises the following components in percentage: 1.4% graphene, 0.5% nano-silicon carbide, 0.15% rare earth oxide powder, 0.4% aluminum nitride whiskers, with the balance being high-purity oxygen-free copper and impurities, the total amount of impurities being less than 0.1%.

[0057] The rare earth oxide powder is a mixture of scandium oxide powder and erbium oxide powder in a weight ratio of 8:4; the graphene has a thickness of 0.30 nm and has 2 layers.

[0058] The preparation method of the graphene-based super copper includes the following steps: (S1) According to the weight percentage, graphene, nano silicon carbide and aluminum nitride whiskers were added to anhydrous ethanol for impregnation, and then 0.8wt% PVP dispersant was added and ultrasonically broken for 3h. Then, the undispersed large particles were removed by centrifugation at 8000rpm for 15min to obtain a suspension. (S2) Rare earth oxide powder, high-purity oxygen-free copper, suspension and 0.3wt% stearic acid are added to a ball mill jar with a ball-to-material ratio of 15:1 and a rotation speed of 800 rpm for 12 hours to form a uniform composite. (S3) The composite is subjected to spark plasma sintering to obtain a dense bulk body; (S4) The dense block is heated to 800℃ and hot rolled in multiple passes using a four-roll mill. The reduction per pass is ≤15% and the total deformation is >80%, to obtain a plate blank with a thickness of 0.5mm. (S5) Cold roll the sheet blank to the target diameter, with a single pass reduction of ≤5% and a total deformation of 20%, to obtain a monofilament prototype; (S6) Using a diamond drawing die, the cold-rolled wire is drawn through multiple passes with a total deformation of >80%, gradually reducing the diameter to the target size. Then, it is heated to 350°C, held for 1.5 hours, and then air-cooled at a rate of 50°C / min.

[0059] The discharge plasma sintering process in step (S3) involves loading the composite into a graphite mold and then placing it into an SPS sintering furnace. The furnace is evacuated to 10⁻⁴ Pa to prevent oxidation. The temperature is then increased to 900°C at a rate of 150°C / min, while a pressure of 80 MPa is applied simultaneously. The temperature is held for 8 minutes, and then cooled to room temperature at a rate of 90°C / min. The resulting dense bulk material has a relative density >99.5%.

[0060] In step (S6), the diamond drawing die contains a 5wt% nano-graphite suspension lubricant, the die cone angle is 12°, the length-to-diameter ratio of the lubrication zone is 3.5, and the drawing speed is controlled at 0.7m / s.

[0061] The insulating varnish of the insulating film is selected from Tritherm. A 981-M TAN.

[0062] The outer diameter of the conductive wire core is 0.4 mm, and the thickness of the insulating varnish film is 0.022 mm.

[0063] The method for preparing the high-temperature resistant speaker voice coil wire includes the following steps: after soaking the conductive wire core in acetone, ultrasonically cleaning and drying, an insulating varnish is applied using a four-coat, four-bake process with the coating speed controlled at 8m / min, and each coating is cured using a stepped high-temperature curing method to obtain the high-temperature resistant speaker voice coil wire.

[0064] The stepped high-temperature curing method is as follows: first stage: 120℃, pre-curing for 2 minutes; second stage: 200℃, curing for 2 minutes; third stage: 300℃, final curing for 2 minutes.

[0065] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: The conductive core is made of high-purity oxygen-free copper.

[0066] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: The graphene-modified copper comprises the following components in percentage: 1.3% graphene, with the balance being high-purity oxygen-free copper and impurities, the total amount of which is less than 0.1%.

[0067] The preparation method of the graphene-based super copper includes the following steps: (S1) According to the weight percentage, graphene was added to anhydrous ethanol for impregnation, and then 0.8wt% PVP dispersant was added and ultrasonically broken for 3h. Then, it was centrifuged at 8000rpm for 15min to remove undispersed large particles and obtain a suspension. (S2) Add high-purity oxygen-free copper, suspension and 0.3wt% stearic acid into a ball mill jar, ball ratio 15:1, speed 800 rpm, ball mill for 12 hours to form a uniform composite. (S3) The composite is subjected to spark plasma sintering to obtain a dense bulk body; (S4) The dense block is heated to 800℃ and hot rolled in multiple passes using a four-roll mill. The reduction per pass is ≤15% and the total deformation is >80%, to obtain a plate blank with a thickness of 0.5mm. (S5) Cold roll the sheet blank to the target diameter, with a single pass reduction of ≤5% and a total deformation of 20%, to obtain a monofilament prototype; (S6) Using a diamond drawing die, the cold-rolled wire is drawn through multiple passes with a total deformation of >80%, gradually reducing the diameter to the target size. Then, it is heated to 350°C, held for 1.5 hours, and then air-cooled at a rate of 50°C / min.

[0068] The discharge plasma sintering process in step (S3) involves loading the composite into a graphite mold and then placing it into an SPS sintering furnace. The furnace is evacuated to 10⁻⁴ Pa to prevent oxidation. The temperature is then increased to 900°C at a rate of 150°C / min, while a pressure of 80 MPa is applied simultaneously. The temperature is held for 8 minutes, and then cooled to room temperature at a rate of 90°C / min. The resulting dense bulk material has a relative density >99.5%.

[0069] In step (S6), the diamond drawing die contains a 5wt% nano-graphite suspension lubricant, the die cone angle is 12°, the length-to-diameter ratio of the lubrication zone is 3.5, and the drawing speed is controlled at 0.7m / s.

[0070] Performance testing The voice coil wires of Example 1 and Comparative Examples 1-2 were used to test their conductivity, resistance, temperature rise, fatigue resistance, thermal conductivity, and high-voltage leakage current.

[0071] The testing method is as follows: Conductivity: The conductivity of the wound wire is tested and calculated according to IACS standards, in units of %.

[0072] Resistance: Use a micro resistance meter (e.g.) Figure 2 As shown in the figure, the DC power supply is set to a constant current source of 70A, and the temperature of the voice coil wire (all wire lengths are 18cm) is measured. The resistance values ​​are measured at 25℃, 150℃, and 180℃, respectively, in mΩ.

[0073] Temperature rise: Fix the voice coil wire (each wire length is 18cm) to the test fixture (e.g.) Figure 1 (As shown) After that, it was placed in a temperature control chamber, the temperature of which was set to 120°C, and baked for 1 hour, then cooled down for 8 hours. Then, the DC power supply was set to a constant current source of 70A, and the temperature was raised from room temperature to 180°C, and then cooled down for 15 hours. The above method is one cycle, and a total of 3 test cycles were performed to test the time required for it to rise from room temperature to 180°C, in seconds.

[0074] Fatigue resistance: The test was conducted using a wire swing tester with a swing load of 500g, a swing angle of 60° to the left and right, a swing frequency of 30 times / min, and the number of times the wire broke completely.

[0075] Thermal conductivity: The thermal conductivity is tested according to GB / T 22588 standard, and the unit is W / (m·K).

[0076] High voltage leakage current: Take voice coil wire (1m in length) and use a (HI-POT Tester) high voltage tester to measure the leakage current under a continuous 3000V DC current for 5 seconds. The unit is mA.

[0077] The test results are shown in Table 1 below:

[0078] As shown in Table 1 above, the high-temperature resistant speaker voice coil wire of the present invention uses graphene super copper with high conductivity. Its composition has a higher conductivity and better heat dissipation and high-temperature resistance through multi-phase synergy. Under the same energy, the resistance rises more slowly and the temperature rises more slowly. It also has lower bending resistance and high voltage leakage current, which is more conducive to the continuous operation of the voice coil wire and extends its service life.

[0079] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A high-temperature resistant loudspeaker voice coil wire, characterized in that: It includes a conductive core and an insulating varnish film covering the conductive core. The conductive core is graphene-copper and has a conductivity of 102-118% IACS.

2. The high-temperature resistant loudspeaker voice coil wire according to claim 1, characterized in that: The graphene-modified copper comprises the following components in percentage: 1.2-1.5% graphene, 0.4-0.6% nano-silicon carbide, 0.08-0.17% rare earth oxide powder, 0.3-0.5% aluminum nitride whiskers, with the balance being high-purity oxygen-free copper and impurities, the total amount of impurities being less than 0.1%.

3. The high-temperature resistant loudspeaker voice coil wire according to claim 2, characterized in that: The rare earth oxide powder is a mixture of scandium oxide powder and erbium oxide powder in a weight ratio of 5-10:3-7; the graphene has a thickness of <0.34nm and has 1-3 layers.

4. A high-temperature resistant loudspeaker voice coil wire according to claim 2 or 3, characterized in that: The preparation method of the graphene-based super copper includes the following steps: (S1) According to the weight percentage, graphene, nano silicon carbide and aluminum nitride whiskers are added to anhydrous ethanol for impregnation, then 0.8wt% PVP dispersant is added and ultrasonically broken for 2-3 hours, and then centrifuged at 5000-8000rpm for 10-20 minutes to remove undispersed large particles to obtain a suspension. (S2) Add rare earth oxide powder, high-purity oxygen-free copper, suspension and 0.3wt% stearic acid into a ball mill jar, ball-to-material ratio 15:1, speed 600-800rpm, ball mill for 10-12h to form a uniform composite. (S3) The composite is subjected to spark plasma sintering to obtain a dense bulk body; (S4) The dense block is heated to 800℃ and hot rolled in multiple passes using a four-roll mill. The reduction per pass is ≤15% and the total deformation is >80%, to obtain a plate blank with a thickness of 0.5mm. (S5) Cold roll the sheet blank to the target diameter, with a single pass reduction of ≤5% and a total deformation of 20%, to obtain a monofilament prototype; (S6) Using a diamond drawing die, the cold-rolled wire is drawn through multiple passes with a total deformation of >80%, gradually reducing the diameter to the target size. Then, it is heated to 350℃, held for 1.5 hours, and then air-cooled at a rate of ≤50℃ / min.

5. The high-temperature resistant loudspeaker voice coil wire according to claim 4, characterized in that: The discharge plasma sintering process in step (S3) involves loading the composite into a graphite mold and then placing it into an SPS sintering furnace. The furnace is evacuated to 10⁻⁴ Pa to prevent oxidation. The temperature is then increased to 900°C at a rate of 150°C / min, while a pressure of 80 MPa is applied simultaneously. The temperature is held for 8 minutes, and then cooled to room temperature at a rate of >80°C / min. The resulting dense bulk material has a relative density >99.5%.

6. The high-temperature resistant loudspeaker voice coil wire according to claim 4, characterized in that: In step (S6), the diamond drawing die contains a 5wt% nano-graphite suspension lubricant, the die cone angle is 12°, the length-to-diameter ratio of the lubrication zone is ≥3, and the drawing speed is controlled at 0.5-1m / s.

7. The high-temperature resistant loudspeaker voice coil wire according to claim 1, characterized in that: The heat resistance rating of the insulating varnish film reaches 220°C or higher, and the insulating varnish of the insulating varnish film is selected from Tritherm. A 981-M TAN or Tritherm A981-H.

8. The high-temperature resistant loudspeaker voice coil wire according to claim 1, characterized in that: The outer diameter of the conductive wire core is 0.04mm-0.5mm, and the thickness of the insulating varnish film is 0.02-0.03mm.

9. A method for preparing a high-temperature resistant loudspeaker voice coil wire as described in any one of claims 1-8, characterized in that: The process includes the following steps: after soaking the conductive wire core in acetone, ultrasonically cleaning and drying, an insulating varnish is applied using a four-coat, four-bake process with the coating speed controlled at 5-20 m / min, and each coating is cured using a stepped high-temperature curing method to obtain a high-temperature resistant speaker voice coil wire.

10. The method for preparing a high-temperature resistant loudspeaker voice coil wire according to claim 9, characterized in that: The stepped high-temperature curing method is as follows: first stage: 120℃, pre-curing for 2 minutes; second stage: 200℃, curing for 2 minutes; third stage: 300℃, final curing for 2 minutes.

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