A high-temperature wire resistant to 1000℃ and its preparation method

Abstract

This application belongs to the field of wire and cable manufacturing technology, and discloses a high-temperature wire with a resistance of 1000℃ and its manufacturing method. The high-temperature wire comprises, from the inside out, a composite conductor, a transition layer, a composite insulation layer, and a protective layer. The manufacturing steps include: Step 1: preparation of the composite conductor; Step 2: magnetron sputtering of a nano-alumina transition layer; Step 3: preparation of the gradient composite insulation layer; Step 4: curing of the quartz fiber protective layer. The high-temperature wire of this invention can withstand long-term operation at 1000℃, with a bending fatigue life exceeding 3000 cycles. Compared with traditional wires, it increases the upper limit of temperature resistance by 40%, reduces space occupation by 50%, and improves resistance stability by 6 times, meeting the high-reliability power transmission requirements of extreme scenarios such as aero-engines, nuclear fusion devices, and ultra-high power electric arc furnaces.

Description

Technical Field

[0001] This application belongs to the field of wire and cable technology, specifically relating to a high-temperature wire resistant to 1000℃ and its preparation method. Background Technology

[0002] High-temperature wires are characterized by high temperature resistance, insulation, fire resistance, corrosion resistance, and aging resistance. They are generally made of high-temperature resistant, high-strength materials and processed using special techniques. There are many types of high-temperature wires, commonly 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 frequently used as 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 industries, high-temperature wires are used in components such as engines, turbines, and rocket engines. These components need to operate at extremely high temperatures. For example, the combustion chamber temperature of a new generation of turbofan engines reaches 1200-1400℃, requiring sensor cables to be laid within a space with a diameter of ≤3mm, while simultaneously withstanding temperature shocks greater than 100 times per second (ΔT≥800℃). Therefore, wires and cables capable of withstanding extremely high temperatures are required.

[0004] However, existing high-temperature resistant cables generally suffer from the following problems: most high-temperature wire conductors use pure nickel or copper, but pure nickel is expensive and has weak conductivity, while copper is prone to oxidation and failure under long-term high temperatures; the insulation layer mostly relies on a single mica or magnesium oxide, which has insufficient mechanical strength and temperature resistance stability; the interface bonding between the metal conductor and the insulation layer is poor, and structural failure is easily caused by the difference in thermal expansion coefficients; existing products generally have a lifespan of less than 500 hours when operating continuously at 1000℃ and above, which is difficult to meet the long-term needs of nuclear power, aerospace and other scenarios.

[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 the insulation layer leads to interface cracking; and the high-temperature decomposition of inorganic materials (mica, ceramics) and organic adhesives (silicone resin) creates weak points in the insulation. Summary of the Invention

[0006] Purpose of the invention: To address the shortcomings of the prior art, this application provides a high-temperature wire and its preparation method, solving the following problems: improving the conductivity and oxidation resistance of the conductor during long-term operation above 1000℃; enhancing the bonding strength between the insulation layer and the conductor interface to prevent high-temperature delamination; 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 1000℃, wherein the high-temperature wire comprises, from the inside out, a composite conductor, a transition layer, a composite insulation layer, and a protective layer.

[0008] The composite conductor is a nickel-clad copper stranded wire, with a nickel layer accounting for 30%-50%, and a conductor diameter of 1.2±0.1mm after stranding; its resistivity at 1000℃ is ≤2×10⁻⁶. -8 Ω·m, 60% lower than pure nickel conductors, copper core ensures low resistance, and outer nickel coating provides high-temperature oxidation protection.

[0009] The transition layer is a nano-alumina coating with a thickness of 10-50 μm, formed by magnetron sputtering. Its gradient transition coefficient of thermal expansion reduces thermal stress at the conductor-insulator interface. The preferred thickness of the transition layer is 40 μm, which can block high-temperature diffusion of copper ions and prevent degradation of the insulation layer's conductivity.

[0010] The composite insulation layer comprises an inner layer and an outer layer: the inner layer is a fluorophlogopite mica tape containing 5%-10% boron nitride filler, 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, enabling rapid heat dissipation.

[0011] 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 silicon carbide fiber braided sleeve provides skeletal support, and the nano-ceramic slurry fills and sinters to form a continuous phase, with no crack propagation after 50 thermal shock cycles. The overall thermal conductivity of the composite insulation layer is ≥15W / (m·K), avoiding the accumulation of local hot spots.

[0012] The protective layer is a high-purity quartz glass fiber woven layer, impregnated with high-temperature resistant silicone resin and cured. The quartz fiber woven layer resists mechanical wear, and the silicone resin, after curing, achieves a hardness of 6H 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℃, comprising the following steps:

[0014] Step 1: Preparation of composite conductor

[0015] After being alkali-washed, acid-washed, and water-washed, the copper wire core is immersed in a nickel sulfamate electroplating solution for electroplating. The nickel-plated copper wire is then stranded in layers, with an outer layer strand pitch of 3±0.1mm and an inner layer strand pitch of 2±0.1mm, resulting in a conductor diameter of 1.2±0.1mm. This differentiated strand pitch optimizes bending stress distribution and improves dynamic bending life. Annealing is performed in an annealing furnace, followed by cooling. The nickel-copper interface is annealed with hydrogen to form a metallurgical bond, avoiding the risk of peeling due to thermal expansion differences in traditional electroplating layers. The stranded diameter of 1.2mm matches the wiring requirements in confined spaces (bending radius ≤4D), and the layered strand pitch design enhances resistance to fatigue fracture.

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

[0017] The surface of the composite conductor was cleaned by argon ion bombardment to remove the surface oxide layer; then sputter deposition was performed using a high-purity Al2O3 target, with the following process parameters: sputtering power 400-500W, substrate temperature 250±1℃, and vacuum degree 4.8-5.2×10⁻⁶. -4 The deposition rate was 2-2.2 μm / min, with a total deposition thickness of 40 ± 1 μm. After deposition, annealing was performed to relieve internal stress in the coating. The 40 ± 1 μm thickness prevented high-temperature diffusion of copper ions, thus avoiding degradation of the conductivity of the insulating layer.

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

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

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

[0021] Step 4: Curing of the quartz fiber protective layer

[0022] A quartz fiber braided layer is wrapped around the insulation layer; then, high-temperature resistant silicone resin is impregnated 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 >1×10⁻⁶. 14 Ω·cm.

[0023] Specifically, in step 1, the electroplating parameters are: current density 4A / dm³. 2 Temperature 55℃, time 30min, nickel layer thickness accounts for 20% (0.06mm) of the single wire diameter.

[0024] Specifically, in step 1, the annealing process involves introducing high-purity hydrogen into the annealing furnace, holding it at 950°C for 30 minutes, and then removing it after cooling it to 200°C in the furnace.

[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, with the BN filler accounting for 8% ± 1% and having a particle size ≤ 5 μm.

[0027] Specifically, in step 3, the high-frequency hot pressing is performed at a frequency of 27MHz, a temperature of 700℃±10℃, a pressure of 8MPa, and a holding time of 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 formulation is: 50wt% Al2O3, 30wt% SiO2, 20wt% ZrO2, with ethanol as the solvent and a solid content of 65%.

[0029] Specifically, in step 3, the silicon carbide fiber is twill woven with a weave 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 sintering density of 3.4 g / cm³. 3 .

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

[0032] Beneficial effects: This invention, through the design of nickel-clad copper stranded wire composite conductor (nickel layer accounting for 30%-50%), retains the high conductivity of copper core while utilizing the high-temperature oxidation resistance of nickel layer, so that the resistance increase of the conductor is less than 5% at 1000℃, thus overcoming the problem of the incompatibility between conductivity and heat resistance of traditional materials.

[0033] This invention combines the thermal expansion gradient matching of the magnetron sputtered nano-alumina transition layer with the copper ion diffusion barrier effect to significantly reduce interfacial thermal stress and improve insulation stability.

[0034] This invention innovatively employs a composite insulation structure of boron nitride-reinforced fluorophlogopite inner layer and silicon carbide fiber ceramic outer layer, achieving 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 endow the wire with excellent mechanical strength and corrosion resistance. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the cross-sectional structure of the high-temperature line.

[0036] In the diagram: 1. Composite conductor; 2. Transition layer; 3-1. Inner layer of composite insulation; 3-2. Outer layer of composite insulation; 4. Protective layer.

[0037] Figure 2 Images recorded for aging tests.

[0038] Figure 3 Images documenting bending tests after aging. Detailed Implementation

[0039] The technical solution of this application will be described in detail below through embodiments, but the scope of protection of this application is not limited to the embodiments described. All quantities mentioned in this invention are by weight.

[0040] Example 1

[0041] Step 1:

[0042] After being treated with alkaline washing (10% NaOH solution), acid washing (10% H2SO4), and water washing, the copper wire core is immersed in a nickel sulfamate plating solution for electroplating; plating parameters: current density 4A / dm³ 2 Temperature 55℃, time 30min, nickel layer thickness accounts for 20% (0.06mm) of the single wire diameter;

[0043] Three nickel-plated copper wires were stranded in layers (outer layer strand pitch 3mm, inner layer strand pitch 2mm), resulting in a conductor diameter of 1.2mm. The conductor was then placed in an annealing furnace, which was filled with high-purity hydrogen and held at 950℃ for 30 minutes. After cooling to 200℃ in the furnace, the conductor was removed, increasing its elongation to 28%.

[0044] Step 2:

[0045] The surface of the composite conductor was cleaned by argon ion bombardment (200W power, 10min) to remove the surface oxide layer; then sputter deposition was performed using a high-purity Al2O3 target, with the following process parameters: sputtering power 450W, substrate temperature 250℃, and vacuum degree 5×10⁻⁶. -4 Pa, deposition rate 2 μm / min, total thickness 40 μm; after deposition, annealing at 800℃ in an argon atmosphere for 10 minutes to eliminate internal stress in the coating (XRD shows grain size ≤50 nm).

[0046] Step 3:

[0047] Inner layer (fluorine-phlogopite tape):

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

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

[0050] Silicon carbide fiber twill weave (weave angle 45°±2°, density 85%); then impregnate with nano-ceramic slurry (formulation: Al2O3 50wt%, SiO2 30wt%, ZrO2 20wt%, solvent is ethanol, solid content 65%).

[0051] After impregnation, segmented sintering is performed: First stage: 800℃ / 1h (heating rate 5℃ / min), solvent evaporation; Second stage: 1250℃ / 1h (nitrogen protection), forming a dense ceramic layer (density ≥3.3g / cm³). 3 ).

[0052] Step 4:

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

[0054] The high-temperature wire obtained in Example 1 has a bending radius of 4D and a conductor resistivity of 1.78 × 10⁻⁶. -8 The insulation strength was Ω·m, the transition layer bonding strength was 18.5 MPa, the insulation breakdown voltage was 38 kV / mm (1200℃), and the tensile strength was 240 MPa. Aging tests were conducted at 1000℃, and the results are shown in the table below.

[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 table below. Figure 2 , Figure 3 As shown.

[0058]

[0059] As can be seen from the figure, at 1000℃, the high-temperature wire of this invention is superior to commercially available conventional high-temperature wires.

[0060] Example 2

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

[0062] Example 3

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

[0064] Example 4

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

[0066] The test data for Examples 1-4 are as follows:

[0067]

[0068] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of this application. The high-temperature wire described in this invention has an overall temperature resistance of up to 1000℃ for long-term operation (1200℃ for short periods), a bending fatigue life of over 3000 cycles (4D radius), and a 40% increase in the upper limit of temperature resistance, a 50% reduction in space occupation, and a 6-fold increase in resistance stability compared to traditional wires. It can meet the high-reliability power transmission requirements of extreme scenarios such as aero-engines, nuclear fusion devices, and ultra-high power electric arc furnaces.

Claims

1. A high-temperature wire resistant to 1000℃, characterized in that, The high-temperature wire, from the inside out, includes a composite conductor, a transition layer, a composite insulation layer, and a protective layer. The composite conductor is a nickel-clad copper stranded wire, with a nickel layer accounting for 30%-50%, and the conductor diameter after stranding is 1.2±0.1mm; The transition layer is a nano-alumina coating with a thickness of 10-50 μm, formed by magnetron sputtering. The composite insulation layer comprises an inner layer and an outer layer: the inner layer is a fluorophlogopite tape containing 5%-10% boron nitride filler, 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 woven layer, impregnated with high-temperature resistant silicone resin and cured. The high-temperature wire is obtained through the following steps: Step 1: Preparation of composite conductor After being washed with alkali, acid, and water, the copper wire core is immersed in nickel sulfamate electroplating solution for electroplating. The nickel-plated copper wire is then stranded in layers with an outer layer strand pitch of 3±0.1mm and an inner layer strand pitch of 2±0.1mm. The conductor diameter after stranding is 1.2±0.1mm. The wire is then 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 argon ion bombardment to remove the surface oxide layer; then sputter deposition was performed using a high-purity Al2O3 target, with the following process parameters: sputtering power 400-500W, substrate temperature 250±1℃, and vacuum degree 4.8-5.2×10⁻⁶. -4 Pa, deposition rate 2-2.2 μm / min, total deposition thickness 40±1 μm; After deposition, annealing is performed to eliminate internal stress in the coating; Step 3: Preparation of gradient composite insulating layer Inner layer, fluorophlogopite mica tape: the mica tape is spirally wound with an overlap rate of 50% and a winding tension of 0.3 N / mm²; after winding, high-frequency hot pressing is performed; Outer layer, silicon carbide fiber ceramic: silicon carbide fibers are twill woven and then impregnated with nano-ceramic slurry. After impregnation, segmented sintering is carried out: the first stage is heated at a rate of 800-900℃ / h and calcined at 800-900℃ for 1-2h; the second stage is calcined at 1200-1300℃ / h for 2-3h under nitrogen protection to form a dense ceramic layer. The nano-ceramic slurry formulation is as follows: Al2O3 50wt%, SiO2 30wt%, ZrO2 20wt%, with ethanol as the solvent and a solid content of 65%. Step 4: Curing of the quartz fiber protective layer A quartz fiber braided layer is wrapped around the insulation layer; then, it is 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.

2. The method for preparing a high-temperature wire resistant to 1000℃ according to claim 1, characterized in that, In step 1, the electroplating parameters are as follows: current density 4A / dm², temperature 55℃, time 30min, and nickel layer thickness accounting for 20% of the diameter of the single wire.

3. The method for preparing a high-temperature wire resistant to 1000℃ according to claim 1, characterized in that, In step 1, the annealing process involves introducing high-purity hydrogen into the annealing furnace, holding the furnace at 950°C for 30 minutes, and then removing the furnace after cooling to 200°C.

4. The method for preparing a high-temperature wire resistant to 1000℃ according to claim 1, characterized in that, In step 2, the annealing is performed at 800°C in an argon atmosphere for 10 minutes.

5. The method for preparing a high-temperature wire resistant to 1000℃ according to claim 1, characterized in that, The mica tape contains BN filler, with BN filler accounting for 8%±1% and particle size ≤5μm.

6. The method for preparing a high-temperature wire resistant to 1000℃ according to claim 1, characterized in that, The high-frequency hot pressing process involves a frequency of 27MHz, a temperature of 700℃±10℃, a pressure of 8MPa, and a holding time of 10 minutes to form a dense, non-porous layer.

7. The method for preparing a high-temperature wire resistant to 1000℃ according to claim 1, characterized in that, The silicon carbide fiber twill weave has a weave angle of 45±2° and a density of 85%.

8. The method for preparing a high-temperature wire resistant to 1000℃ according to claim 1, characterized in that, The outer ceramic layer has a thickness of 0.25 mm and a sintering density of 3.4 g / cm³.

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