A heat and corona resistant enameled wire and a method for manufacturing the same

Abstract

This invention discloses a heat-resistant and corona-resistant enameled wire and its preparation method, relating to the field of cable conductor technology. Using an aluminum-copper alloy as the substrate, an atomic layer deposition technique is used to construct a nickel-copper gradient coating on the surface of silicon carbide fibers. Ultraviolet laser is then used to process gradient holes along the fiber axis. A dynamic rotating magnetic field is employed in response to the nickel layer on the fibers, and ultrasonic waves and pulsed pressure are simultaneously applied to promote the penetration of molten metal along directional channels, improving the conductor's heat resistance degradation caused by low liquid metal filling rate. Finally, in-situ reaction and hot isostatic pressing are used to complete interface strengthening and densification, resulting in a composite conductor. A composite of polyethylene terephthalate and nylon provides flexibility and basic insulation. Plasma-treated boron nitride fibers are exposed to dopamine to obtain aminated boron nitride fibers, which serve as inorganic fibers to construct a high-temperature skeleton and heat dissipation channels, further enhancing the interfacial bonding strength, thus preparing a heat-resistant and corona-resistant enameled wire.

Description

Technical Field

[0001] This invention relates to the field of cable conductor technology, specifically to a heat-resistant and corona-resistant enameled wire and its preparation method. Background Technology

[0002] Enameled wire is widely used in electrical equipment such as motors and transformers, but existing corona-resistant and heat-resistant enameled wires still have some aspects that need improvement. On the one hand, some corona-resistant enameled wires are prone to partial discharge on their surface when high-frequency voltage is applied, leading to accelerated electrical aging. At the same time, the skin effect generated by high-frequency voltage increases rotor resistance, which in turn increases the heat generated by the motor, accelerating thermal aging. Under the combined effect of electricity and heat, the insulation performance of the enameled wire gradually decreases, eventually leading to failure. On the other hand, although traditional corona-resistant enameled wires enhance their resistance to partial discharge and overvoltage by adding metal oxide powder, this structure cannot increase the corona initiation voltage, and its corona resistance performance decreases significantly during stretching. For example, when stretched by 5%, the corona resistance performance decreases by half, and when stretched by 10%, the lifespan decreases by 90%. In addition, existing enameled wires are prone to aging and softening of the insulation layer under high-temperature environments, leading to a decline in insulation performance and making it difficult to meet the requirements of high-temperature environments such as new energy vehicles. Summary of the Invention

[0003] The purpose of this invention is to provide a heat-resistant and corona-resistant enameled wire and its preparation method, so as to solve the problems existing in the prior art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a heat-resistant and corona-resistant enameled wire, comprising the following preparation steps:

[0005] (1) Gradient-coated silicon carbide short fibers are placed horizontally, and gradient holes are processed along the fiber axis using a 355nm wavelength ultraviolet laser with a power of 10W and a pulse frequency of 20kHz. The outer layer pore diameter is 5-10μm, the inner layer pore diameter is 1-3μm, and the depth accounts for 80% of the fiber diameter, thus obtaining perforated short fibers. Then, the perforated short fibers are immersed in aluminum alloy melt at 750℃. The volume fraction of the perforated short fibers is 3-5%, and the aluminum alloy melt composition is 96% Al and the rest is Cu. A rotating magnetic field with an intensity of 1.0T is applied and the rotation speed is 150rpm. Simultaneously, 40kHz ultrasonic waves and 10MPa peak pulse pressure are superimposed. The pulse frequency is 5Hz. After immersion for 5min, hot isostatic pressing is performed at 100MPa pressure for 2h to obtain castings. Composite wires are obtained after the castings are processed and drawn.

[0006] (2) Next, a vertical coating machine is used to coat the surface of the composite conductor with three layers of insulating varnish at a linear speed of 20 m / min to obtain the enameled wire conductor;

[0007] (3) Polyethylene terephthalate and nylon are mixed in a ratio of 6:4. The polyethylene terephthalate resin is of brand WB-8816 and comes from Changzhou Huarun Polyester Co., Ltd. The nylon is nylon 6 with a melting temperature of 250°C. After cooling to 200°C, 0.1-0.3 times the mass of polyethylene terephthalate and amino boron nitride fiber are added. The mixture is kept warm for 1 hour and then twisted into composite fiber. The composite fiber is first wound around the enameled wire conductor, and then further wound with quartz fiber. After pre-curing by infrared radiation at 200°C for 30 seconds, it is hot-pressed at 10MPa pressure and 150°C for 1 hour to obtain the enameled wire conductor.

[0008] Further, the method for preparing gradient-plated silicon carbide short fibers in step (1) is as follows: Ni(CO)4 vapor is injected into the reaction chamber to adsorb onto the surface of the pretreated short fibers. The injection rate is 500-1500 sccm, and the injection time is 10-30 s. The Ni(CO)4 vapor is obtained by vaporizing Ni(CO)4 liquid. The pulse time is 1-3 s, the current density is 10 A / dm², and the pulse frequency is 40 kHz. Unreacted precursors and byproducts are purged with high-purity nitrogen for 5-10 s. H2 is injected at an injection rate of 2000 sccm. The interval is 1-3s, the pulse time is 1-2s, the current density is 5A / dm², and the pulse frequency is 10kHz; then a second sweep-blowing is performed to remove residual gas, completing a single cycle; multiple cycles of deposition are performed at 250℃ until a 0.4-0.6μm nickel transition layer is deposited on the surface of silicon carbide short fibers; then a 1.5-2.5μm copper layer is electroplated at a current density of 3A / dm² using a solution of 200g / L CuSO4 and 50g / L H2SO4, with the remainder being deionized water, to form a nickel-copper gradient interface and obtain gradient-plated silicon carbide short fibers.

[0009] Furthermore, the pre-treated short fiber preparation process is as follows: silicon carbide short fibers with a diameter of 10 μm and a length of 50 μm are soaked in a 10% NaOH aqueous solution at 60°C for 5 min to remove surface oil stains, with a solid-liquid ratio of 1:10. Then, they are soaked in a 5% HNO3 solution for 30 s to remove the oxide layer and undergo acid washing treatment, with a solid-liquid ratio of 1:10. After that, they are ultrasonically cleaned at a frequency of 50 kHz for 10-30 min and rinsed once with deionized water. Finally, they are dried with nitrogen gas.

[0010] Furthermore, the casting processing and drawing process in step (1) is as follows: the billet obtained by continuous casting is rolled to obtain an aluminum alloy rod. The initial rolling temperature is 550°C and the final rolling temperature is 150°C. The obtained aluminum alloy is then cold-drawn.

[0011] Furthermore, the deformation amount is 15% each time during the drawing process, and the material is drawn to 5mm after 6 draws.

[0012] Furthermore, in step (2), the bottom layer of the three-layer insulating varnish is made of polyethylene terephthalate resin and 10% by mass of nano-Al2O3 with a particle size of 50nm. The polyethylene terephthalate resin is of brand WB-8816 and comes from Changzhou Huarun Polyester Co., Ltd., forming a heat-resistant layer with a thickness of 10μm.

[0013] Furthermore, in step (2), the three-layer insulating varnish coating is applied, and the middle layer is made of polyamide-imide and epoxy resin in a mass ratio of 7:3. The polyamide-imide is grade JF1070 and comes from Suzhou Jufeng Insulation Materials Co., Ltd.; the epoxy resin is grade EPR627 and comes from HEXION in the United States; forming a corona-resistant layer with a thickness of 9μm.

[0014] Furthermore, in step (2), the outer layer of the three-layer insulating varnish coating is made of ECTFE resin containing 5wt% SiO2 nanoparticles with a particle size of 20nm, purchased from Zhejiang Provincial Research Institute Co., Ltd., forming a hydrophobic protective layer with a thickness of 5μm.

[0015] Furthermore, the diameter of the composite fiber in step (3) is 0.12-0.2 mm.

[0016] Furthermore, in step (3), the diameter of the quartz fiber is 0.2 mm.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0018] This invention prepares a highly conductive and heat-resistant composite wire by combining a copper-nickel-based gradient plating layer with perforated short fibers and an aluminum alloy matrix, and improves the corona resistance by combining a polyethylene terephthalate / nylon insulation layer with amino-modified boron nitride fibers, thus preparing a heat-resistant and corona-resistant enameled wire.

[0019] First, using an aluminum-copper alloy as the substrate, short fibers are added to prepare the conductor. A thin nickel layer is first deposited on the surface of the silicon carbide fiber using atomic layer deposition (ALD) as a transition layer to enhance adhesion. Then, a thick copper layer is deposited to balance the interfacial contact with the metal substrate, constructing a nickel-copper gradient coating. Combined with ultraviolet laser processing, gradient pores are created along the fiber axis, forming continuous penetration channels to improve metal filling efficiency. The gradient coating design balances interfacial wettability and reaction inhibition, reducing the contact angle, and the coating acts as a "metal bridge" to enhance interfacial bonding strength. Subsequently, a dynamic rotating magnetic field and the response of the fiber nickel layer are used to achieve axially oriented pores within the fiber during liquid metal infiltration. Simultaneous application of ultrasonic waves and pulsed pressure promotes the penetration of liquid metal along the oriented pores, improving the conductor's heat resistance degradation caused by low liquid metal filling rate. The laser-magnetic field combined process achieves a three-in-one synergy of "pore orientation, fiber axial alignment, and metal penetration control," reducing porosity and optimizing fiber distribution uniformity. Finally, in-situ reaction and hot isostatic pressing are used to complete interfacial strengthening and densification, resulting in the composite conductor.

[0020] Secondly, the composite of polyethylene terephthalate and nylon provides flexibility and basic insulation; aminated boron nitride fibers are used as inorganic fibers to construct a high-temperature skeleton and heat dissipation channels; the C=O of aminated boron nitride fibers and polyethylene terephthalate form amide bonds through nucleophilic attack, further enhancing the interfacial bonding strength; strong interfacial bonding reduces microcrack initiation and blocks the electrolyte penetration path caused by corona discharge. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The following embodiments describe a method for testing various indicators of a heat-resistant and corona-resistant enameled wire:

[0023] Corona resistance: Refer to GB / T 24122-2009.

[0024] High temperature resistance: Refer to GB / T 4074.6-2008.

[0025] Strength: Refer to GB / T 4074.3-2008

[0026] Example 1; (1) Silicon carbide short fibers with a diameter of 10 μm and a length of 50 μm were soaked in a 10% NaOH aqueous solution at 60°C for 5 min to remove surface oil stains. The solid-liquid ratio was 1:10. Subsequently, a 5% NaOH aqueous solution was used. Immersion in HNO3 solution for 30 seconds to remove the oxide layer followed by acid washing (solid-liquid ratio 1:10), then ultrasonic cleaning at 50kHz for 10 minutes, and rinsing once with deionized water. Finally, drying with nitrogen. Ni(CO)4 vapor is injected into the reaction chamber to adsorb onto the pretreated short fiber surface at a rate of 500 sccm for 10 seconds. The Ni(CO)4 vapor is prepared by vaporization of liquid Ni(CO)4, with a pulse duration of 1 second, a current density of 10 A / dm², and a pulse frequency of 40 kHz. Unreacted precursors and byproducts are purged with high-purity nitrogen for 5 seconds. H2 is then injected at a rate of 2000 sccm for 1 second, with a pulse duration of 1 second, a current density of 5 A / dm², and a pulse frequency of 10 kHz. A second purging is then performed to remove residual gas, completing a single cycle. Multiple cyclic depositions are performed at 250℃ until a 0.4 μm nickel transition layer is deposited on the silicon carbide short fiber surface. Finally, a 200 g / L Cu solution is used. S Using O4 and 50 g / L H2SO4 as the electrolyte, with the remainder being deionized water, a 1.5 μm copper layer was electroplated at a current density of 3 A / dm², forming a nickel-copper gradient interface to obtain gradient-plated silicon carbide short fibers. The gradient-plated silicon carbide short fibers were then placed horizontally and subjected to a 355 nm wavelength ultraviolet laser at 10 W power and 20 kHz pulse frequency to process gradient holes along the fiber axis. The outer pore diameter was 5 μm, and the inner pore diameter was 1 μm, with a depth accounting for 80% of the fiber diameter, thus producing perforated short fibers. These perforated short fibers were then immersed in 750 °C aluminum alloy melt, with a volume fraction of 3%. The aluminum alloy melt composition is 96% Al and the remainder is Cu. A rotating magnetic field of 1.0T strength is applied and the melt is run at 150 rpm. Simultaneously, 40 kHz ultrasonic waves and 10 MPa peak pulse pressure are superimposed. The pulse frequency is 5 Hz. After impregnation for 5 minutes, the melt is subjected to hot isostatic pressing at 100 MPa pressure for 2 hours to obtain a casting. The billet obtained by continuous casting is rolled to obtain an aluminum alloy rod. The initial rolling temperature is 550℃ and the final rolling temperature is 150℃. The obtained aluminum alloy is then cold-drawn. The deformation amount is 15% each time, and the composite wire is obtained after 6 passes of drawing to 5 mm.

[0027] (2) Next, a vertical coating machine was used to coat the surface of the composite conductor with three layers of insulating varnish at a linear speed of 20 m / min: the bottom layer was made of polyethylene terephthalate resin and 10% nano-Al2O3 with a particle size of 50 nm. The polyethylene terephthalate resin was of brand WB-8816 and came from Changzhou Huarun Polyester Co., Ltd., forming a heat-resistant layer with a thickness of 10 μm; the middle layer was made of polyamide-imide and epoxy resin in a mass ratio of 7:3. The polyamide-imide was of brand JF1070 and came from Suzhou Jufeng Insulation Materials Co., Ltd.; the epoxy resin was of brand EPR627 and came from HEXION, USA, forming an anti-corona layer with a thickness of 9 μm; the outer layer was made of ECTFE resin containing 5 wt% SiO2 nanoparticles with a particle size of 20 nm and purchased from Zhejiang Provincial Research Institute Co., Ltd., forming a hydrophobic protective layer with a thickness of 5 μm; the enameled wire conductor was obtained.

[0028] (3) Boron nitride fibers with a diameter of 10 μm and urea were ball-milled in a ball mill jar at a mass ratio of 1:70, using zirconia grinding balls as the medium, with a material-to-ball ratio of 1:20, a planetary speed of 350 rpm, a revolution speed of 10 rpm, and a ball milling time of 20 h to obtain aminated boron nitride fibers; polyethylene terephthalate and nylon 6 were mixed in a ratio of 6:4, wherein the polyethylene terephthalate resin brand was WB-8816, which came from Changzhou Huarun Polyester Co., Ltd., and the melting temperature was... At a temperature of 250℃, 0.1 times the mass of polyethylene terephthalate (PET) and amino-boron nitride fibers are added and kept at this temperature for 1 hour. The fibers are then twisted into composite fibers with a diameter of 0.12 mm. Using 0.2 mm diameter quartz fibers as raw materials, the composite fibers are first wound around the enameled wire conductor, and then the quartz fibers are used for further winding. After pre-curing by infrared radiation at 200℃ for 30 seconds, the wire is hot-pressed at 10 MPa pressure and 150℃ for 1 hour to obtain the enameled wire conductor.

[0029] Example 2; (1) Silicon carbide short fibers with a diameter of 10 μm and a length of 50 μm were soaked in a 10% NaOH aqueous solution at 60°C for 5 min to remove surface oil stains, with a solid-liquid ratio of 1:10. Then, they were soaked in a 5% HNO3 solution for 30 s to remove the oxide layer and were acid-washed, with a solid-liquid ratio of 1:10. After that, they were ultrasonically cleaned at a frequency of 50 kHz for 20 min and rinsed once with deionized water. Finally, they were dried by blowing with nitrogen. Ni(CO)4 vapor was injected into the reaction chamber to adsorb onto the surface of the pretreated short fibers. The injection speed was 1000 sccm and the injection time was 20 s. The Ni(CO)4 vapor was obtained by vaporizing Ni(CO)4 liquid. The pulse time was 2 s, the current density was 10 A / dm², and the pulse frequency was 40 kHz. High-purity Unreacted precursors and byproducts were purged with nitrogen for 7.5 s. H2 was then injected at a rate of 2000 sccm for 2 s, with a pulse duration of 1.5 s, a current density of 5 A / dm², and a pulse frequency of 10 kHz. A second purging was then performed to remove residual gases, completing a single cycle. Multiple cycles of deposition were carried out at 250 °C until a 0.5 μm nickel transition layer was deposited on the surface of the silicon carbide short fibers. Then, using a solution of 200 g / L CuSO4 and 50 g / L H2SO4, with the remainder being deionized water, deposition was carried out at 3 A / L. A 2μm copper layer was electroplated at a dm² current density to form a nickel-copper gradient interface, resulting in gradient-plated silicon carbide short fibers. These fibers were then placed horizontally and subjected to a 355nm wavelength ultraviolet laser with a power of 10W and a pulse frequency of 20kHz to process gradient holes along the fiber axis. The outer pore diameter was 7.5μm, and the inner pore diameter was 2μm, with a depth accounting for 80% of the fiber diameter, thus producing perforated short fibers. These perforated short fibers were then immersed in a 750℃ aluminum alloy melt. The volume fraction of the perforated short fibers was 4%, and the aluminum alloy melt composition was 96% Al. The remainder is Cu. A rotating magnetic field of 1.0T strength is applied and the rotation speed is 150rpm. Simultaneously, 40kHz ultrasound and 10MPa peak pulse pressure are superimposed. The pulse frequency is 5Hz. After impregnation for 5 minutes, hot isostatic pressing is performed at 100MPa pressure for 2 hours to obtain the casting. The billet obtained by continuous casting of the casting is rolled to obtain an aluminum alloy rod. The entry rolling temperature is 550℃ and the final rolling temperature is 150℃. The obtained aluminum alloy is cold drawn. The deformation amount is 15% each time. After 6 passes of drawing to 5mm, the composite wire is obtained.

[0030] (2) Next, a vertical coating machine was used to coat the surface of the composite conductor with three layers of insulating varnish at a linear speed of 20 m / min: the bottom layer was made of modified polyethylene terephthalate resin and 12.5% ​​nano-Al2O3 with a particle size of 50 nm. The polyethylene terephthalate resin was of brand WB-8816 and came from Changzhou Huarun Polyester Co., Ltd., forming a heat-resistant layer with a thickness of 10 μm; the middle layer was made of polyamide-imide and epoxy resin in a mass ratio of 7:3. The polyamide-imide was of brand JF1070 and came from Suzhou Jufeng Insulation Materials Co., Ltd.; the epoxy resin was of brand EPR627 and came from HEXION, USA, forming an anti-corona layer with a thickness of 9 μm; the outer layer was made of ECTFE resin containing 5 wt% SiO2 nanoparticles with a particle size of 20 nm and purchased from Zhejiang Provincial Research Institute Co., Ltd., forming a hydrophobic protective layer with a thickness of 5 μm; the enameled wire conductor was obtained.

[0031] (3) Boron nitride fibers with a diameter of 10 μm and urea were ball-milled in a ball mill jar at a mass ratio of 1:70, using zirconia grinding balls as the medium, with a material-to-ball ratio of 1:20, a planetary speed of 350 rpm, a revolution speed of 10 rpm, and a ball milling time of 20 h to obtain aminated boron nitride fibers; polyethylene terephthalate and nylon 6 were mixed in a ratio of 6:4, wherein the polyethylene terephthalate resin brand was WB-8816, which came from Changzhou Huarun Polyester Co., Ltd., and the nylon came from Shanghai Ruibang Engineering Plastics. Limited transparent nylon with a melting temperature of 250℃ is mixed with 0.2 times the mass of polyethylene terephthalate and amino-boron nitride fibers, kept at this temperature for 1 hour, and then twisted into composite fibers with a diameter of 0.16 mm. Using 0.2 mm diameter quartz fibers as raw materials, the composite fibers are first wound around the enameled wire conductor, and then the quartz fibers are used for further winding. After pre-curing by infrared radiation at 200℃ for 30 seconds, the wire is hot-pressed at 10 MPa pressure and 150℃ for 1 hour to obtain the enameled wire conductor.

[0032] Example 3; (1) Silicon carbide short fibers with a diameter of 10 μm and a length of 50 μm were soaked in a 10% NaOH aqueous solution at 60°C for 5 min to remove surface oil stains, with a solid-liquid ratio of 1:10. Then, they were soaked in a 5% HNO3 solution for 30 s to remove the oxide layer and were acid-washed, with a solid-liquid ratio of 1:10. After that, they were ultrasonically cleaned at a frequency of 50 kHz for 30 min and rinsed once with deionized water. Finally, they were dried by blowing with nitrogen. Ni(CO)4 vapor was injected into the reaction chamber to adsorb onto the surface of the pretreated short fibers. The injection speed was 500-1500 sccm and the injection time was 10-30 s. The Ni(CO)4 vapor was obtained by vaporizing Ni(CO)4 liquid. The pulse time was 1-3 s, the current density was 10 A / dm², and the pulse frequency was 40. kHz; Unreacted precursors and byproducts were purged with high-purity nitrogen for 5-10 s, followed by H2 injection at a rate of 2000 sccm for 3 s, a pulse duration of 2 s, a current density of 5 A / dm², and a pulse frequency of 10 kHz; then a second purging was performed to remove residual gas, completing a single cycle; multiple cycles of deposition were performed at 250 °C until a 0.6 μm nickel transition layer was deposited on the surface of the silicon carbide short fibers; then, an electrolyte of 200 g / L CuSO4 and 50 g / L H2SO4, with the remainder being deionized water, was used. A 2.5 μm copper layer was electroplated at a current density of 3 A / dm² to form a nickel-copper gradient interface, resulting in gradient-plated silicon carbide short fibers. The gradient-plated silicon carbide short fibers were placed horizontally, and gradient holes were machined along the fiber axis using a 355 nm wavelength ultraviolet laser at a power of 10 W and a pulse frequency of 20 kHz. The outer pore diameter was 10 μm, and the inner pore diameter was 3 μm with a depth accounting for 80% of the fiber diameter, thus producing perforated short fibers. Subsequently, the perforated short fibers were immersed in 750℃ aluminum alloy melt, with a volume fraction of 5% perforated short fibers and an aluminum alloy melt composition of 96% Al. The aluminum alloy is composed of 5% copper and the remainder is Cu. A rotating magnetic field of 1.0T is applied and the material is run at 150rpm. Simultaneously, 40kHz ultrasound and 10MPa peak pulse pressure are superimposed. The pulse frequency is 5Hz. After impregnation for 5 minutes, the material is subjected to hot isostatic pressing at 100MPa pressure for 2 hours to obtain the casting. The billet obtained by continuous casting is rolled to obtain an aluminum alloy rod. The initial rolling temperature is 550℃ and the final rolling temperature is 150℃. The obtained aluminum alloy is then cold-drawn. The deformation amount is 15% each time, and after 6 passes of drawing to 5mm, a composite wire is obtained.

[0033] (2) Next, a vertical coating machine was used to coat the surface of the composite conductor with three layers of insulating varnish at a linear speed of 20 m / min: the bottom layer was made of polyethylene terephthalate resin and 15% nano-Al2O3 with a particle size of 50 nm. The polyethylene terephthalate resin was of brand WB-8816 and came from Changzhou Huarun Polyester Co., Ltd., forming a heat-resistant layer with a thickness of 10 μm; the middle layer was made of polyamide-imide and epoxy resin in a mass ratio of 7:3. The polyamide-imide was of brand JF1070 and came from Suzhou Jufeng Insulation Materials Co., Ltd.; the epoxy resin was of brand EPR627 and came from HEXION, USA, forming an anti-corona layer with a thickness of 9 μm; the outer layer was made of ECTFE resin containing 5 wt% SiO2 nanoparticles with a particle size of 20 nm and purchased from Zhejiang Provincial Research Institute Co., Ltd., forming a hydrophobic protective layer with a thickness of 5 μm; the enameled wire conductor was obtained.

[0034] (3) Boron nitride fibers with a diameter of 10 μm and urea were ball-milled in a ball mill jar at a mass ratio of 1:70, using zirconia grinding balls as the medium, with a material-to-ball ratio of 1:20, a planetary speed of 350 rpm, a revolution speed of 10 rpm, and a ball milling time of 20 h to obtain aminated boron nitride fibers; polyethylene terephthalate and nylon 6 were mixed in a ratio of 6:4, wherein the polyethylene terephthalate resin brand was WB-8816, which came from Changzhou Huarun Polyester Co., Ltd., and the nylon came from Shanghai Ruibang Engineering Plastics. Limited transparent nylon with a melting temperature of 250℃ is mixed with 0.3 times the mass of polyethylene terephthalate and amino-boron nitride fibers, kept at this temperature for 1 hour, and then twisted into composite fibers with a diameter of 0.2 mm. Using 0.2 mm diameter quartz fibers as raw materials, the composite fibers are first wound around the enameled wire conductor, and then the quartz fibers are used for further winding. After pre-curing by infrared radiation at 200℃ for 30 seconds, the wire is hot-pressed at 10 MPa pressure and 150℃ for 1 hour to obtain the enameled wire conductor.

[0035] Comparative Example 1; The difference between Comparative Example 1 and Example 2 lies in step (1). Step (1) is changed to: immersing silicon carbide short fibers with a diameter of 10 μm and a length of 50 μm in a 10% NaOH aqueous solution at 60°C for 5 min to remove surface oil, with a solid-liquid ratio of 1:10, followed by using a 5% NaOH aqueous solution. Immersion in HNO3 solution for 30 seconds to remove the oxide layer followed by acid washing (solid-liquid ratio 1:10), then ultrasonic cleaning at 50kHz for 20 minutes, and rinsing once with deionized water. Finally, drying with nitrogen. Ni(CO)4 vapor is injected into the reaction chamber to adsorb onto the surface of the pretreated short fibers at an injection rate of 1000 sccm for 20 seconds. The Ni(CO)4 vapor is prepared by vaporization of Ni(CO)4 liquid, with a pulse duration of 2 seconds, a current density of 10A / dm², and a pulse frequency of 40kHz. Unreacted precursors and byproducts are purged with high-purity nitrogen for 7.5 seconds, followed by H2 injection at an injection rate of 2000 sccm for 2 seconds, a pulse duration of 1.5 seconds, a current density of 5A / dm², and a pulse frequency of 10kHz. A second purging is then performed to remove residual gases, completing a single cycle. Multiple cyclic deposition is performed at 250℃ until a 0.5μm nickel transition layer is deposited on the surface of the silicon carbide short fibers. The nickel-plated silicon carbide short fibers are then... A horizontally placed fiber was subjected to a 355nm wavelength ultraviolet laser with a power of 10W and a pulse frequency of 20kHz to create gradient pores along the fiber axis. The outer pore diameter was 7.5μm, and the inner pore diameter was 2μm with a depth of 80% of the fiber diameter, thus producing perforated short fibers. These perforated short fibers were then immersed in molten aluminum alloy at 750℃. The perforated short fibers had a volume fraction of 4%, and the molten aluminum alloy consisted of 96% Al and the remainder Cu. A rotating magnetic field of 1.0T was applied, and the fibers were rotated at 150rpm. The process involves simultaneously superimposing 40kHz ultrasound and 10MPa peak pulse pressure at a pulse frequency of 5Hz, impregnating for 5 minutes, and then performing hot isostatic pressing at 100MPa pressure for 2 hours to obtain a casting. The billet obtained by continuous casting of the casting is rolled to obtain an aluminum alloy rod with an entry rolling temperature of 550℃ and a final rolling temperature of 150℃. The obtained aluminum alloy is then cold-drawn with a deformation amount of 15% each time, and after 6 passes of drawing to 5mm, a composite wire is obtained. The remaining steps are the same as in Example 2.

[0036] Comparative Example 2; The difference between Comparative Example 2 and Example 2 lies in step (1). Step (1) is changed to: immersing silicon carbide short fibers with a diameter of 10 μm and a length of 50 μm in a 10% NaOH aqueous solution at 60°C for 5 minutes to remove surface oil, with a solid-liquid ratio of 1:10, followed by using a 5% NaOH aqueous solution. Immersion in HNO3 solution for 30 seconds to remove the oxide layer followed by acid washing (solid-liquid ratio 1:10), then ultrasonic cleaning at 50kHz for 20 minutes, and rinsing once with deionized water. Finally, drying with nitrogen gas. Ni(CO)4 vapor is injected into the reaction chamber to adsorb onto the pretreated short fiber surface at an injection rate of 1000 sccm for 20 seconds. The Ni(CO)4 vapor is prepared by vaporization of liquid Ni(CO)4, with a pulse duration of 2 seconds, a current density of 10 A / dm², and a pulse frequency of 40kHz. Unreacted precursors and byproducts are purged with high-purity nitrogen for 7.5 seconds, followed by H2 injection at an injection rate of 2000 sccm for 2 seconds, a pulse duration of 1.5 seconds, a current density of 5 A / dm², and a pulse frequency of 10kHz. A second purging is then performed to remove residual gas, completing a single cycle. Multiple cyclic depositions are performed at 250℃ until a 0.5μm nickel transition layer is deposited on the silicon carbide short fiber surface. Then, a 200% concentration of [missing information - likely a specific concentration or value] is used. A 2μm copper layer was electroplated using a solution of g / L CuSO4 and 50g / L H2SO4, with the remainder being deionized water, at a current density of 3A / dm², forming a nickel-copper gradient interface to obtain gradient-plated silicon carbide short fibers. Subsequently, the gradient-plated silicon carbide short fibers were immersed in a 750℃ aluminum alloy melt. The volume fraction of the gradient-plated silicon carbide short fibers was 4%, and the aluminum alloy melt composition was 96% Al and the remainder Cu. A rotating magnetic field of 1.0T was applied, and the mixture was rotated at 150 rpm. The process involves simultaneously superimposing 40kHz ultrasound and 10MPa peak pulse pressure at a pulse frequency of 5Hz, impregnating for 5 minutes, and then performing hot isostatic pressing at 100MPa pressure for 2 hours to obtain a casting. The billet obtained by continuous casting of the casting is rolled to obtain an aluminum alloy rod with an entry rolling temperature of 550℃ and a final rolling temperature of 150℃. The obtained aluminum alloy is then cold-drawn with a deformation amount of 15% each time, and after 6 passes of drawing to 5mm, a composite wire is obtained. The remaining steps are the same as in Example 2.

[0037] Comparative Example 3; The difference between Comparative Example 3 and Example 2 lies in step (1). Step (1) is changed to soaking silicon carbide short fibers with a diameter of 10 μm and a length of 50 μm in a 10% NaOH aqueous solution at 60°C for 5 min to remove surface oil stains, with a solid-liquid ratio of 1:10. Then, the fibers are soaked in a 5% HNO3 solution for 30 s to remove the oxide layer and undergo acid washing treatment, with a solid-liquid ratio of 1:10. After that, the fibers are ultrasonically cleaned at a frequency of 50 kHz for 20 min and rinsed once with deionized water. Finally, they are dried with nitrogen. Ni(CO)4 vapor is injected into the reaction chamber to adsorb onto the surface of the pretreated short fibers. The injection speed is 1000 sccm and the injection time is 20 s. The Ni(CO)4 vapor is obtained by vaporizing Ni(CO)4 liquid. The pulse time is 2 s, the current density is 10 A / dm², and the pulse frequency is 40 kHz. Unreacted precursors and byproducts were purged with high-purity nitrogen for 7.5 s, followed by H2 injection at a rate of 2000 sccm for 2 s, a pulse duration of 1.5 s, a current density of 5 A / dm², and a pulse frequency of 10 kHz. A second purging was then performed to remove residual gases, completing a single cycle. Multiple cyclic depositions were then performed at 250 °C until a 0.5 μm nickel transition layer was deposited on the surface of the silicon carbide short fibers. Finally, a mixture of 200 g / L CuSO4 and 50 g / L H2SO4, with the remainder being deionized water, was deposited. Using an electrolyte, a 2μm copper layer was electroplated at a current density of 3A / dm² to form a nickel-copper gradient interface, resulting in gradient-plated silicon carbide short fibers. The gradient-plated silicon carbide short fibers were placed horizontally, and gradient pores were machined along the fiber axis using a 355nm wavelength ultraviolet laser at a power of 10W and a pulse frequency of 20kHz. The outer pore diameter was 7.5μm, and the inner pore diameter was 2μm, with a depth accounting for 80% of the fiber diameter, thus producing perforated short fibers. Subsequently, the perforated short fibers were immersed in 750℃ aluminum alloy melt, with a volume fraction of 4% for the perforated short fibers. The melt composition consists of 96% Al and the remainder Cu. A 40kHz ultrasonic wave and a 10MPa peak pulse pressure are applied at a pulse frequency of 5Hz. After impregnation for 5 minutes, the melt undergoes hot isostatic pressing at 100MPa for 2 hours to obtain a casting. The billet obtained from continuous casting is rolled to obtain an aluminum alloy rod. The initial rolling temperature is 550℃, and the final rolling temperature is 150℃. The resulting aluminum alloy is then cold-drawn. Each deformation is 15%, and the alloy is drawn to 5mm in 6 passes to obtain a composite wire. The remaining steps are the same as in Example 2.

[0038] Comparative Example 4; The difference between Comparative Example 4 and Example 2 lies in step (1). Step (1) is changed to: immersing silicon carbide short fibers with a diameter of 10 μm and a length of 50 μm in a 10% NaOH aqueous solution at 60°C for 5 minutes to remove surface oil, with a solid-liquid ratio of 1:10, followed by using a 5% NaOH aqueous solution. The oxide layer was removed by soaking in HNO3 solution for 30 seconds, followed by pickling at a solid-liquid ratio of 1:10. The mixture was then ultrasonically cleaned at 50 kHz for 20 minutes and rinsed once with deionized water. Finally, it was dried with nitrogen. Subsequently, silicon carbide short fibers were immersed in molten aluminum alloy at 750°C. The volume fraction of the silicon carbide short fibers was 4%, and the aluminum alloy melt composition was 96% Al and the remainder Cu. Hot isostatic pressing was performed at 100 MPa for 2 hours to obtain a casting. The billet obtained from continuous casting was rolled to obtain an aluminum alloy rod at an entry rolling temperature of 550°C and a final rolling temperature of 150°C. The resulting aluminum alloy was then cold-drawn, with a deformation of 15% per pass, and drawn to 5 mm in 6 passes to obtain a composite wire. The remaining steps were the same as in Example 2.

[0039] Comparative Example 5; The difference between Comparative Example 5 and Example 2 lies in step (3). Step (3) is changed to: polyethylene terephthalate and nylon 6 are mixed in a ratio of 6:4, wherein the polyethylene terephthalate resin brand is WB-8816, which comes from Changzhou Huarun Polyester Co., Ltd., and the melting temperature is 250°C. Then, it is twisted into a composite fiber with a diameter of 0.16 mm. It is used as raw material with quartz fiber with a diameter of 0.2 mm. First, the composite fiber is wound around the enameled wire conductor, and then the quartz fiber is used for further winding. After pre-curing by infrared radiation at 200°C for 30 s, it is hot-pressed at 10 MPa pressure and 150°C for 1 h to obtain the enameled wire conductor. The remaining steps are the same as in Example 2.

[0040] Example of effect

[0041] Table 1 below shows the performance analysis results of a heat-resistant and corona-resistant enameled wire using Examples 1 to 3 and Comparative Examples 1 to 5 of the present invention.

[0042] Table 1

[0043]

[0044] A comparison of the heat resistance experimental data from the examples and comparative examples reveals that this invention uses an aluminum-copper alloy as the substrate and adds short fibers to prepare the conductor. First, a thin nickel layer is deposited on the surface of the silicon carbide fiber using atomic layer deposition technology as a transition layer to enhance the bonding force. Then, a thick copper layer is deposited to balance the interfacial contact with the metal substrate, constructing a nickel-copper gradient coating. Combined with ultraviolet laser, gradient pores are processed along the fiber axis to form continuous penetration channels and improve the metal filling efficiency. The gradient coating design takes into account both interfacial wettability and reaction inhibition, reduces the contact angle, and the coating can act as a "metal bridge" to enhance the interfacial bonding strength. Subsequently, a dynamic rotating magnetic field and the response of the fiber nickel layer are used to achieve axially oriented arrangement of the pores inside the fiber during the liquid metal impregnation process. Ultrasonic waves and pulsed pressure are applied simultaneously to promote the penetration of the liquid metal along the oriented channels, improving the conductor's heat resistance deterioration caused by low liquid metal filling rate. A comparison of the elongation experimental data of the examples and comparative examples reveals that the present invention achieves a three-in-one synergistic effect of "pore orientation arrangement - fiber axial alignment - metal penetration control" through a laser-magnetic field combined process, resulting in reduced porosity and optimized fiber distribution uniformity. Finally, interface strengthening and densification are completed through in-situ reaction and hot isostatic pressing to obtain composite wires. A comparison of the corona resistance experimental data of the examples and comparative examples reveals that the present invention utilizes polyethylene terephthalate (PET) and nylon composites to provide flexibility and basic insulation. Plasma-treated boron nitride fibers are exposed to dopamine to obtain aminated boron nitride fibers, which serve as inorganic fibers to construct a high-temperature skeleton and heat dissipation channels. The C=O bonds of the aminated boron nitride fibers and PET form amide bonds through nucleophilic attack, further enhancing the interfacial bonding strength. Strong interfacial bonding reduces microcrack initiation and blocks the electrolyte penetration path caused by corona discharge.

[0045] 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 implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A heat-resistant and corona-resistant enameled wire, characterized in that, The preparation steps include the following: (1) Gradient-coated silicon carbide short fibers are placed horizontally, and gradient holes are processed along the fiber axis using a 355nm wavelength ultraviolet laser with a power of 10W and a pulse frequency of 20kHz. The outer layer pore diameter is 5-10μm, the inner layer pore diameter is 1-3μm, and the depth accounts for 80% of the fiber diameter, thus obtaining perforated short fibers. Then, the perforated short fibers are immersed in aluminum alloy melt at 750℃, with a volume fraction of 3-5%. A rotating magnetic field of 1.0T intensity is applied and the fiber is run at a speed of 150rpm. Simultaneously, 40kHz ultrasonic waves and 10MPa peak pulse pressure are superimposed, with a pulse frequency of 5Hz. After immersion for 5min, hot isostatic pressing is performed at 100MPa pressure for 2h to obtain a casting. The casting is then processed and drawn to obtain a composite wire. (2) Next, a vertical coating machine is used to coat the surface of the composite conductor with three layers of insulating varnish at a linear speed of 20 m / min to obtain the enameled wire conductor; (3) Mix polyethylene terephthalate and nylon in a 6:4 ratio, melt at 250°C, cool to 200°C and add 0.1-0.3 times the mass of polyethylene terephthalate aminated boron nitride fiber, keep warm for 1 hour, and then twist into composite fiber; first, wind the composite fiber into the enameled wire conductor, and then further wind it with quartz fiber; after pre-curing by infrared radiation at 200°C for 30 seconds, hot press at 10MPa pressure and 150°C for 1 hour to obtain the enameled wire conductor.

2. The heat-resistant and corona-resistant enameled wire according to claim 1, characterized in that, The method for preparing gradient-plated silicon carbide short fibers in step (1) is as follows: Ni(CO)4 vapor is injected into the reaction chamber to adsorb onto the surface of the pretreated short fibers. The injection rate is 500-1500 sccm, and the injection time is 10-30 s. The Ni(CO)4 vapor is obtained by vaporizing Ni(CO)4 liquid. The pulse time is 1-3 s, the current density is 10 A / dm², and the pulse frequency is 40 kHz. Unreacted precursors and byproducts are purged with high-purity nitrogen for 5-10 s. H2 is then injected at a rate of 2000 sccm and an injection time of 1 s. -3s, pulse time 1-2s, current density 5A / dm², pulse frequency 10kHz; then a second sweep-blowing to remove residual gas, completing a single cycle; multiple cycles of deposition at 250℃ until a 0.4-0.6μm nickel transition layer is deposited on the surface of silicon carbide short fibers; then, using 200g / L CuSO4 and 50g / L H2SO4 as electrolytes, with the remainder being deionized water, a 1.5-2.5μm copper layer is electroplated at a current density of 3A / dm² to form a nickel-copper gradient interface, obtaining gradient-plated silicon carbide short fibers.

3. The heat-resistant and corona-resistant enameled wire according to claim 2, characterized in that, The pretreated short fiber preparation process is as follows: silicon carbide short fibers with a diameter of 10 μm and a length of 50 μm are soaked in a 10% NaOH aqueous solution at 60°C for 5 min to remove surface oil stains, with a solid-liquid ratio of 1:

10. Then, they are soaked in a 5% HNO3 solution for 30 s to remove the oxide layer and undergo acid washing treatment, with a solid-liquid ratio of 1:

10. After that, they are ultrasonically cleaned at a frequency of 50 kHz for 10-30 min and rinsed once with deionized water. Finally, they are dried with nitrogen gas.

4. The heat-resistant and corona-resistant enameled wire according to claim 1, characterized in that, The casting processing and drawing process in step (1) is as follows: the billet obtained by continuous casting is rolled to obtain an aluminum alloy rod. The initial rolling temperature is 550℃ and the final rolling temperature is 150℃. The obtained aluminum alloy is then cold-drawn.

5. The heat-resistant and corona-resistant enameled wire according to claim 4, characterized in that, The deformation amount is 15% each time it is drawn, and it is drawn to 5mm after 6 draws.

6. The heat-resistant and corona-resistant enameled wire according to claim 1, characterized in that, In step (2), the three-layer insulating varnish coating is made of polyethylene terephthalate resin and 10% by mass of nano-Al2O3 with a particle size of 50nm. The polyethylene terephthalate resin is grade WB-8816 and comes from Changzhou Huarun Polyester Co., Ltd., forming a heat-resistant layer with a thickness of 10μm.

7. The heat-resistant and corona-resistant enameled wire according to claim 1, characterized in that, In step (2), the three-layer insulating varnish is applied. The middle layer is made of polyamide-imide and epoxy resin in a mass ratio of 7:

3. The polyamide-imide is brand JF1070 and comes from Suzhou Jufeng Insulation Materials Co., Ltd. The epoxy resin is brand EPR627 and comes from HEXION in the United States. A corona-resistant layer with a thickness of 9μm is formed.

8. The heat-resistant and corona-resistant enameled wire according to claim 1, characterized in that, In step (2), the outer layer of the three-layer insulating varnish coating is made of ECTFE resin containing 5wt% SiO2 nanoparticles with a particle size of 20nm, purchased from Zhejiang Provincial Research Institute Co., Ltd., forming a hydrophobic protective layer with a thickness of 5μm.

9. The heat-resistant and corona-resistant enameled wire according to claim 1, characterized in that, The diameter of the composite fiber in step (3) is 0.12-0.2 mm.

10. The heat-resistant and corona-resistant enameled wire according to claim 1, characterized in that, In step (3), the diameter of the quartz fiber is 0.2 mm.

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