1000 DEG C-resistant high-temperature wire and preparation method thereof

Abstract

The invention belongs to the technical field of wire and cable preparation, and discloses a 1000 DEG C-resistant high-temperature wire and a preparation method thereof.The high-temperature wire comprises a composite conductor, a transition layer, a composite insulating layer and a protective layer from inside to outside, and the preparation method comprises the steps that 1, the composite conductor is prepared; 2, performing magnetron sputtering on a nano aluminum oxide transition layer; 3, preparing a gradient composite insulating layer; and 4, curing the quartz fiber protective layer. The whole high-temperature wire can resist the temperature of 1000 DEG C for long-term operation, the bending fatigue life exceeds 3000 times, compared with a traditional wire, the temperature resistance upper limit is improved by 40%, the occupied space is reduced by 50%, the resistance stability is improved by 6 times, and the high-reliability power transmission requirements under the extreme scenes of aero-engines, nuclear fusion devices, ultra-high-power electric arc furnaces and the like can be met.

Description

Technical Field

[0001] The present application belongs to the technical field of wires and cables, and specifically relates to a high-temperature wire resistant to 1000°C and a preparation method thereof. Background Art

[0002] High-temperature wires offer high-temperature resistance, insulation, fire retardancy, corrosion resistance, and aging resistance. They are generally made of high-temperature-resistant, high-strength materials processed through specialized processes. There are many types of high-temperature wires, including fluoroplastic-insulated high-temperature wires, silicone rubber-insulated high-temperature wires, silicone rubber-insulated braided wires, multi-core high-temperature cables, and mineral-insulated fire-resistant cables. In the electronics industry, they are commonly used for temperature compensation wires, low-temperature-resistant wires, high-temperature heating wires, aging-resistant wires, and flame-retardant wires.

[0003] In the aerospace and nuclear power sectors, high-temperature wires are used in components such as engines, turbines, and rocket engines. These components must operate at extremely high temperatures. For example, the combustion chamber of a new generation of turbofan engines reaches temperatures of 1200-1400°C. Sensor cables must be laid within a space with a diameter of ≤3mm and withstand temperature shocks exceeding 100 times per second (ΔT ≥ 800°C). Therefore, wires and cables that can withstand extremely high temperatures are required.

[0004] However, existing high-temperature resistant cables generally have the following problems: most high-temperature wire conductors use pure nickel or copper, but pure nickel is expensive and has weak conductivity, and copper is easily oxidized and fails under long-term high temperatures; the insulation layer mostly relies on a single mica or magnesium oxide, which lacks mechanical strength and temperature stability; the interface bonding between the metal conductor and the insulation layer is poor, and structural failure is easily caused by differences in thermal expansion coefficients; the lifespan of existing products is generally less than 500 hours when working continuously at 1000°C and above, which makes it difficult to meet the long-term needs of scenarios such as nuclear power and aerospace.

[0005] The main technical bottlenecks are: it is difficult for a single metal or alloy to balance the contradiction between high-temperature oxidation resistance (such as Ni, Mo) and conductivity (such as Cu, Ag); the difference in thermal expansion coefficients between the conductor and insulation layer leads to interface cracking; inorganic materials (mica, ceramics) and organic adhesives (silicone resin) decompose at high temperatures, forming weak points in insulation. Summary of the Invention

[0006] Purpose of the invention: In response to the shortcomings of the existing technology, the present application provides a high-temperature wire and a preparation method thereof to solve the following problems: improving the conductivity and oxidation resistance of the conductor when working for a long time at above 1000°C; enhancing the bonding strength between the insulation layer and the conductor interface to prevent high-temperature stratification; and extending the service life of the high-temperature wire in extreme environments (≥1000 hours).

[0007] Technical solution: The present invention provides a high-temperature wire that can withstand temperatures of 1000°C. The high-temperature wire comprises a composite conductor, a transition layer, a composite insulation layer, and a protective layer from the inside out.

[0008] The composite conductor is a nickel-clad copper stranded wire, with the nickel layer accounting for 30%-50%. The conductor diameter after stranding is 1.2±0.1mm; the resistivity at 1000℃ is ≤2×10 -8 Ω·m, which is 60% lower than that of pure nickel conductors. The copper core ensures low resistance characteristics, and the outer nickel coating provides high-temperature anti-oxidation protection.

[0009] The transition layer is a nano-alumina coating with a thickness of 10-50 μm, formed via a magnetron sputtering process. The gradient transition in thermal expansion coefficient reduces thermal stress at the conductor-insulator interface. The transition layer, preferably 40 μm thick, blocks the high-temperature diffusion of copper ions and prevents conductivity degradation in the insulation layer.

[0010] The composite insulation layer includes an inner layer and an outer layer: the inner layer is a fluorphlogopite tape containing 5%-10% boron nitride filler and is formed by high-frequency hot pressing; the addition of a small amount of boron nitride filler can improve the thermal conductivity of the mica tape and achieve rapid heat dissipation.

[0011] The outer layer is a braided silicon carbide fiber sleeve coated with a nano-ceramic slurry and sintered at high temperature to form a continuous, dense structure. The silicon carbide fiber sleeve provides skeletal support, while the nano-ceramic slurry fills and sinters to form a continuous phase. It survived 50 thermal shock cycles without crack propagation. The overall thermal conductivity of the composite insulation layer is ≥15W / (m·K), preventing the accumulation of localized hot spots.

[0012] The protective layer is a high-purity quartz glass fiber braided layer, impregnated with high-temperature resistant silicone resin and cured. The quartz fiber braided layer resists mechanical wear, and the silicone resin has a hardness of 6H after curing and is resistant to acid and alkali corrosion.

[0013] The present invention also provides a method for preparing the above-mentioned high-temperature wire resistant to 1000°C, comprising the following steps:

[0014] Step 1: Composite Conductor Preparation

[0015] After alkali washing, acid washing, and water washing, the copper wire core is immersed in a nickel sulfamate electroplating solution for electroplating. The nickel-plated copper wire is layered and twisted, with an outer layer lay length of 3±0.1mm and an inner layer lay length of 2±0.1mm. The conductor diameter after twisting is 1.2±0.1mm. Differentiated lay lengths optimize bending stress distribution and improve dynamic bending life. Annealing is carried out in an annealing furnace and then cooled after annealing. The nickel-copper interface forms a metallurgical bond through hydrogen annealing, avoiding the risk of peeling caused by thermal expansion differences in traditional electroplating. The twisted diameter of 1.2mm meets the requirements of wiring in narrow spaces (bending radius ≤ 4D), and the layered lay length design improves fatigue fracture resistance.

[0016] Step 2: Magnetron sputtering of nano-alumina transition layer

[0017] The surface of the composite conductor was cleaned by bombarding with argon ions to remove the surface oxide layer; then sputtering deposition was performed. The target material used was a high-purity Al2O3 target. The process parameters were: sputtering power 400-500W, substrate temperature 250±1℃, vacuum degree 4.8-5.2×10 -4 Pa, deposition rate 2-2.2μm / min, total deposition thickness 40±1μm; after deposition, annealing is performed to eliminate internal stress in the coating. The 40±1μm thickness blocks the high-temperature diffusion of copper ions and prevents deterioration of the insulation layer's conductivity.

[0018] Step 3: Preparation of gradient composite insulation layer

[0019] Inner layer (fluorphlogopite tape): spirally wound with mica tape, with an overlap rate of 50% and a winding tension of 0.3N / mm 2 After winding, high-frequency hot pressing is performed. After high-frequency hot pressing, the thermal conductivity is ≥5W / (m·K), the breakdown voltage is ≥30kV / mm, and the porosity is <0.1%.

[0020] Outer layer (silicon carbide fiber ceramic): Silicon carbide fiber twill weave, then impregnate nano-ceramic slurry, and then perform segmented sintering after impregnation: the first stage is heated at a rate of 800-900℃ / h, and calcined at 800-900℃ for 1-2h; the second stage: under nitrogen protection, the heating rate is 1200-1300℃ / h, and calcined at 1200-1300℃ for 2-3h to form a dense ceramic layer.

[0021] Step 4: Curing of the Quartz Fiber Protective Layer

[0022] The quartz fiber braid is wrapped around the insulating layer; then impregnated with high-temperature resistant silicone resin for 30-60 seconds; after impregnation, gradient curing is performed: 1-2 hours at 200±5℃, 1-2 hours at 500±5℃, and 30-60 minutes at 800±5℃. After curing, the high-temperature wire is obtained. The gradient curing process eliminates internal stress, and the volume resistivity at 1200℃ is greater than 1×10 14 Ω·cm.

[0023] Specifically, in step 1, the electroplating parameters are: current density 4A / dm 2 , temperature 55℃, time 30min, nickel layer thickness accounts for 20% of the single wire diameter (0.06mm).

[0024] Specifically, in step 1, the annealing is as follows: high-purity hydrogen is introduced into the annealing furnace, the temperature is kept at 950° C. for 30 minutes, and the furnace is cooled to 200° C. before being taken out.

[0025] Specifically, in step 2, the annealing is performed at 800° C. in an argon atmosphere for 10 minutes.

[0026] Specifically, in step 3, the mica tape contains BN filler, the BN filler accounts for 8%±1%, and the particle size is ≤5μm.

[0027] Specifically, in step 3, the high-frequency hot pressing is performed at a frequency of 27 MHz, a temperature of 700° C.±10° C., a pressure of 8 MPa, and pressure maintenance for 10 minutes to form a dense non-porous layer (SEM shows a porosity of <0.1%).

[0028] Specifically, in step 3, the nano-ceramic slurry formula is: Al2O3 50wt%, SiO2 30wt%, ZrO2 20wt%, the solvent is ethanol, and the solid content is 65%.

[0029] Specifically, in step 3, the silicon carbide fiber is twill woven with a braiding angle of 45°±2° and a density of 85%.

[0030] Specifically, in step 3, the outer ceramic layer has a thickness of 0.25 mm and a sintered density of 3.4 g / cm 3 .

[0031] Specifically, in step 4, the impregnated high-temperature resistant silicone resin is added with 5% silicon carbide powder with a particle size of 1 μm.

[0032] Beneficial effect: The present invention adopts a nickel-clad copper stranded wire composite conductor design (the nickel layer accounts for 30%-50%). While retaining the high conductivity of the copper core, it utilizes the high-temperature oxidation resistance of the nickel layer to make the conductor resistance increment less than 5% at 1000°C, thus overcoming the difficult problem of the compatibility of conductivity and heat resistance of traditional materials.

[0033] The present invention combines the thermal expansion gradient matching of the magnetron sputtering nano-aluminum oxide transition layer with the copper ion diffusion barrier effect, significantly reducing interface thermal stress and improving insulation stability.

[0034] The present invention innovatively adopts a composite insulation structure of a boron nitride-reinforced fluorphlogopite inner layer and a silicon carbide fiber ceramic outer layer to achieve synergistic optimization of thermal conductivity ≥15W / (m·K) and breakdown strength 35kV / mm, effectively suppressing high-temperature hot spots; the outer quartz fiber protective layer and high-temperature resistant silicone resin curing process give the wire excellent mechanical strength and corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the cross-section structure of the high-temperature wire.

[0036] In the figure: 1 composite conductor; 2 transition layer; 3-1 inner layer of composite insulation layer; 3-2 outer layer of composite insulation layer; 4 protective layer.

[0037] Figure 2 Record pictures for aging test.

[0038] Figure 3 Record pictures of the bend test after aging. DETAILED DESCRIPTION

[0039] The technical solution of the present application is described in detail below through examples, but the scope of protection of the present application is not limited to the examples. The parts described in the present invention are all calculated by mass.

[0040] Example 1

[0041] Step 1:

[0042] The copper wire core was alkaline washed (10% NaOH solution), acid washed (10% H2SO4), and washed with water, and then immersed in nickel sulfamate electroplating solution for electroplating; electroplating parameters: current density 4A / dm 2 , temperature 55℃, time 30min, nickel layer thickness accounts for 20% of the single wire diameter (0.06mm);

[0043] Three nickel-plated copper wires were twisted in layers (outer layer lay length 3mm, inner layer lay length 2mm). The conductor diameter after twisting was 1.2mm. The wires were placed in an annealing furnace, and high-purity hydrogen was introduced into the furnace. The temperature was maintained at 950°C for 30 minutes. After cooling to 200°C, the wires were removed from the furnace. The elongation of the conductor increased to 28%.

[0044] Step 2:

[0045] The surface of the composite conductor was cleaned by argon ion bombardment (power 200 W, time 10 min) to remove the surface oxide layer; then sputtering deposition was performed. The target material used was a high-purity Al2O3 target. The process parameters were: sputtering power 450 W, substrate temperature 250 °C, vacuum degree 5×10 -4 Pa, deposition rate 2 μm / min, total thickness 40 μm; after deposition, annealing was completed at 800 °C in argon atmosphere for 10 minutes to eliminate the internal stress of the coating (XRD showed that the grain size was ≤50 nm).

[0046] Step 3:

[0047] Inner layer (fluorphlogopite tape):

[0048] Mica tape is spirally wound (overlap rate 50%) with a winding tension of 0.3N / mm 2 After winding, high-frequency hot pressing is performed: frequency 27MHz, temperature 700℃±10℃, pressure 8MPa, and pressure holding for 10 minutes to form a dense non-porous layer;

[0049] Outer layer (silicon carbide fiber ceramic):

[0050] Silicon carbide fibers were twill-woven (braid angle 45°±2°, density 85%) and then impregnated with a nano-ceramic slurry (formula: Al2O3 50wt%, SiO2 30wt%, ZrO2 20wt%, ethanol as solvent, solid content 65%).

[0051] After impregnation, the sintering was carried out in stages: the first stage: 800℃ / 1h (heating rate 5℃ / min) to volatilize the solvent; the second stage: 1250℃ / 1h (nitrogen protection) to form a dense ceramic layer (density ≥3.3g / cm 3 ).

[0052] Step 4:

[0053] A quartz fiber braid (braiding density 90%) is wrapped around the insulating layer; then impregnated with high-temperature resistant silicone resin (added with 5% silicon carbide micropowder, particle size 1 μm) for 30 seconds; gradient curing: 200°C / 1h (pre-curing) → 500°C / 1h (intermediate curing) → 800°C / 30min (final curing), with a hardness of up to 6H (GB / T6739 standard).

[0054] The bending radius of the high-temperature wire obtained in Example 1 is 4D, and the conductor resistivity is 1.78×10 -8 Ω·m, the transition layer bonding strength is 18.5MPa, the insulation layer breakdown voltage is 38kV / mm (1200℃), the tensile strength is 240MPa, and the aging test is carried out at 1000℃. The results are shown in the following table:

[0055]

[0056]

[0057] The high temperature wire obtained in Example 1 is compared with conventional high temperature wires on the market, as shown in the following table and Figure 2 、 Figure 3 shown.

[0058]

[0059] It can be seen from the figure that under the environment of 1000°C, the high temperature wire of the present invention is better than the conventional high temperature wire on the market.

[0060] Example 2

[0061] The basic steps of Example 2 are substantially the same as those of Example 1, except that, in step 1, five nickel-plated copper wires are twisted.

[0062] Example 3

[0063] The basic steps of Example 3 are substantially the same as those of Example 1, except that, in step 1, eight nickel-plated copper wires are twisted.

[0064] Example 4

[0065] The basic steps of Example 4 are substantially the same as those of Example 1, except that, in step 1, 13 nickel-plated copper wires are twisted.

[0066] The test data of Examples 1 to 4 are as follows:

[0067]

[0068] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. The high-temperature wire described in the present invention has an overall temperature resistance of 1000°C for long-term operation (1200°C for short-term operation) and a bending fatigue life of over 3000 times (4D radius). Compared with traditional wires, the upper temperature limit is increased by 40%, the space occupied is reduced by 50%, and the resistance stability is increased by 6 times. It can meet the high-reliability power transmission requirements in extreme scenarios such as aircraft engines, nuclear fusion devices, and ultra-high power arc furnaces.

Claims

1. A high temperature wire resistant to 1000°C, characterized in that: The high-temperature wire, a high-temperature wire resistant to 1000°C, comprises a composite conductor, a transition layer, a composite insulation layer, and a protective layer from the inside out: The composite conductor is a nickel-clad copper stranded wire, with the nickel layer accounting for 30%-50%, and the conductor diameter after stranding is 1.2±0.1mm; The transition layer is a nano-aluminum oxide coating with a thickness of 10-50 μm, formed by a magnetron sputtering process; The composite insulation layer includes an inner layer and an outer layer: the inner layer is a fluorphlogopite tape containing 5%-10% boron nitride filler and is formed by high-frequency hot pressing; the outer layer is a silicon carbide fiber braided sleeve, the surface of which is coated with nano-ceramic slurry and sintered at high temperature to form a continuous and dense structure; The protective layer is a high-purity quartz glass fiber braided layer impregnated with high-temperature resistant silicone resin and cured.

2. The method for preparing a high-temperature wire resistant to 1000°C according to claim 1, characterized in that The steps include: Step 1: Composite Conductor Preparation After alkali washing, acid washing, and water washing, the copper wire core is immersed in a nickel sulfamate electroplating solution for electroplating. The nickel-plated copper wire is layered and twisted, with an outer layer lay length of 3±0.1mm and an inner layer lay length of 2±0.1mm. The conductor diameter after twisting is 1.2±0.1mm. The copper wire is annealed in an annealing furnace and cooled after annealing. Step 2: Magnetron sputtering of nano-alumina transition layer The surface of the composite conductor was cleaned by bombarding with argon ions to remove the surface oxide layer; then sputtering deposition was performed. The target material used was a high-purity Al2O3 target. The process parameters were: sputtering power 400-500W, substrate temperature 250±1℃, vacuum degree 4.8-5.2×10 -4 Pa, deposition rate 2-2.2 μm / min, total deposition thickness 40 ± 1 μm; After deposition is completed, annealing is performed to eliminate internal stress in the coating; Step 3: Preparation of gradient composite insulation layer Inner layer, fluorphlogopite tape: spirally wound with mica tape, with an overlap rate of 50% and a winding tension of 0.3N / mm2; After winding is completed, high frequency hot pressing is performed; Outer layer, silicon carbide fiber ceramic: silicon carbide fiber twill weave, then impregnate nano-ceramic slurry, and then perform segmented sintering after impregnation: the first stage is calcined at 800-900℃ / h at a heating rate of 800-900℃ for 1-2h; the second stage: under nitrogen protection, the heating rate is 1200-1300℃ / h, and calcined at 1200-1300℃ for 2-3h to form a dense ceramic layer; Step 4: Curing of the Quartz Fiber Protective Layer Wrap the quartz fiber braided layer around the insulation layer; then impregnate with high-temperature resistant silicone resin for 30-60 seconds; After the impregnation is completed, gradient curing is performed: 1-2 hours at 200±5°C, 1-2 hours at 500±5°C, and 30-60 minutes at 800±5°C. After the curing is completed, the high-temperature wire is obtained.

3. The method for preparing a high-temperature wire resistant to 1000°C according to claim 2, characterized in that: In step 1, the electroplating parameters are: current density 4A / dm 2 , temperature 55℃, time 30min, nickel layer thickness accounts for 20% of the single wire diameter.

4. The method for preparing a high-temperature wire resistant to 1000°C according to claim 2, characterized in that: In step 1, the annealing is as follows: high-purity hydrogen is introduced into the annealing furnace, the temperature is kept at 950° C. for 30 minutes, and the furnace is cooled to 200° C. before being taken out.

5. The method for preparing a high-temperature wire resistant to 1000°C according to claim 2, characterized in that: In step 2, the annealing is performed at 800° C. in an argon atmosphere for 10 minutes.

6. The method for preparing a high-temperature wire resistant to 1000°C according to claim 2, characterized in that: The mica tape contains BN filler, the BN filler accounts for 8%±1%, and the particle size is ≤5μm.

7. The method for preparing a high-temperature wire resistant to 1000°C according to claim 2, characterized in that: The high-frequency hot pressing is carried out at a frequency of 27 MHz, a temperature of 700° C.±10° C., a pressure of 8 MPa, and a pressure holding time of 10 minutes to form a dense and non-porous layer.

8. The method for preparing a high-temperature wire resistant to 1000°C according to claim 2, characterized in that: In step 3, the nano-ceramic slurry formula is: Al2O3 50wt%, SiO2 30wt%, ZrO2 20wt%, the solvent is ethanol, and the solid content is 65%.

9. The method for preparing a high-temperature wire resistant to 1000°C according to claim 2, characterized in that: The silicon carbide fiber is twill-woven with a weaving angle of 45±2° and a density of 85%.

10. The method for preparing a high-temperature wire resistant to 1000°C according to claim 2, characterized in that: The outer ceramic layer has a thickness of 0.25 mm and a sintered density of 3.4 g / cm 3 .

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