Ultra-high temperature self-adapting insulated cable of a composite and method of manufacturing the same

Abstract

The application discloses a kind of superhigh temperature self-adaptive insulated cable of composite and preparation method thereof, which uses carbon nanotube fiber bundle as conductor, multiple layer aerogel-ceramic nanofiber composite felt as insulator, stress buffer layer formed by negative thermal expansion coefficient material is arranged between layers, and the outer sheath is chemical vapor infiltration SiC carbon fiber braided sleeve.The cable of the application has the advantages of ultra-light, high thermal stability, self-adaptive sealing and strong thermal shock resistance, and is suitable for extreme high temperature environment above 800 DEG C;The preparation method includes supercritical drying, pre-stretching winding and other key processes, to realize the high performance and reliability of the cable.

Description

Technical Field

[0001] This invention relates to the field of special cable technology, and in particular to a composite ultra-high temperature adaptive insulated cable and its preparation method. Background Technology

[0002] Existing high-temperature cables for aerospace applications mostly employ ceramicized silicone rubber, mica tape-wrapped metal conductors, or metal sheath structures (such as nickel alloys or stainless steel). Their limitations are: 1. Heavy weight, which is not conducive to spacecraft weight reduction; 2. Poor flexibility and low installation adaptability; 3. Mismatch in thermal expansion coefficients may lead to insulation layer cracking; 4. The maximum withstand temperature is mostly limited to below 600℃.

[0003] Although some studies have used carbon fiber or silicon carbide fiber as conductors, problems such as high-temperature oxidation and poor insulation interface stability still exist. Summary of the Invention

[0004] The technical problem to be solved by this invention is that existing high-temperature cables cannot simultaneously meet the comprehensive requirements of "ultra-high temperature resistance, lightweight, flexibility, and high insulation interface stability".

[0005] The technical solution adopted by the present invention to solve its technical problem is: a high temperature resistant cable of 800℃, which includes, from the inside to the outside, a conductor layer, a first insulation layer, a stress buffer layer, a second insulation layer and an outer sheath;

[0006] The conductor layer is formed by twisting together oriented carbon nanotube fiber bundles, and the surface of the oriented carbon nanotube fiber bundles is coated with a boron nitride nano-coating with a thickness of 1-2 μm.

[0007] The first insulating layer is a silicon carbide nanofiber felt impregnated with silica aerogel, with a density of 0.15-0.25 g / cm³. 3 Furthermore, a three-dimensional network structure is formed through electrospinning;

[0008] The stress buffer layer is a composite film of a material with a negative thermal expansion coefficient and polycarbosilane, wherein the material with a negative thermal expansion coefficient is selected from at least one of ZrW2O8 or HfMo2O8.

[0009] The second insulating layer is a composite felt of alumina aerogel and yttrium oxide-stabilized zirconium oxide fibers;

[0010] The outer sheath is a carbon fiber woven sheath coated with SiC by chemical vapor deposition.

[0011] The diameter of a single carbon nanotube fiber bundle is 0.2-0.3 mm, and the conductor layer is formed by twisting 8-15 bundles of the carbon nanotube fiber bundles together, resulting in a conductor layer diameter of 1.2-1.8 mm after twisting.

[0012] The thickness of the first insulating layer is 0.6-1.0 mm, and the thermal conductivity is ≤0.025 W / m·K; the thickness of the second insulating layer is 1.0-1.5 mm, and the upper limit of temperature resistance is ≥1000℃.

[0013] The stress buffer layer has a thickness of 0.08-0.12 mm and is a composite film that has been pre-stretched by 10%-15% at 200-250°C and then spirally wound around the first insulating layer.

[0014] The outer sheath has a thickness of 0.2-0.4 mm, and the porosity of the carbon fiber braided sheath is ≤5% after being filled with SiC.

[0015] A central reinforcing core is provided on the inner side of the conductor layer, and a hollow arc-shaped extrusion cover is provided on the outer side of the central reinforcing core.

[0016] A method for preparing a high-temperature cable resistant to 800℃ includes the following steps:

[0017] S1: Preparation of conductor layer: Carbon nanotube fiber bundles are continuously prepared by floating catalyst method. The carbon nanotube fiber bundles are heat-treated at 950-1050℃ for 1-2 hours in an ammonia atmosphere to form a boron nitride nano-coating on their surface. Then, 8-15 bundles of the coated carbon nanotube fiber bundles are twisted together to obtain conductor layer.

[0018] S2: Preparation of the first insulating layer: Silicon carbide nanofiber mat is prepared by electrospinning, and silica aerogel precursor is infiltrated into the silicon carbide nanofiber mat using supercritical drying technology. After drying, the first insulating layer is obtained; the first insulating layer is then coated on the outside of the conductor layer.

[0019] S3: Preparation of stress buffer layer: ZrW2O8 or HfMo2O8 is deposited on polyimide film using magnetron sputtering technology, and then pyrolyzed to transform into a composite film of material with negative thermal expansion coefficient and polycarbosilane; the composite film is pre-stretched by 10%-15% at 200-250℃, and then spirally wound around the first insulating layer to form a stress buffer layer.

[0020] S4: Preparation of the second insulating layer: Alumina aerogel precursor is infiltrated into yttrium oxide-stabilized zirconia fiber felt, and the second insulating layer is obtained after curing treatment; the second insulating layer is wrapped around the stress buffer layer;

[0021] S5: Preparation of outer sheath: A carbon fiber braided sleeve is placed outside the second insulation layer. SiC is filled into the pores of the carbon fiber braided sleeve using a reactive melt infiltration process, and then densified by chemical vapor infiltration to form the outer sheath.

[0022] S6: Shaping treatment: The structure obtained in step S5 is kept at 300-400℃ for 2-3 hours in an inert atmosphere to obtain a high-temperature cable resistant to 800℃.

[0023] In step S2, the conditions for supercritical drying are: temperature 300-350℃, pressure 15-20MPa, and holding time 2-3h.

[0024] In step S5, the conditions for the reaction melt infiltration process are as follows: the molar ratio of Si powder to C powder as raw materials is 1:1.2, and the reaction is carried out in an argon atmosphere at 1500-1600℃ for 3-4 hours, so that SiC fills the pores of the carbon fiber braided sleeve.

[0025] The beneficial effects of this invention are:

[0026] (1) The composite ultra-high temperature adaptive insulated cable and its preparation method of the present invention have a cable density of only 1.8 g / m, which is 1 / 5 of that of traditional nickel-based cables and 1 / 7 of that of 316L stainless steel sheathed cables, greatly reducing the weight load of spacecraft and other equipment;

[0027] (2) After continuous heating in an air atmosphere at 800℃ for 100 hours, the insulation resistance still remains >10. 8 Ω·m, capacitance change rate <3%, breakdown voltage >4kV, meeting the insulation and conductivity stability requirements under extreme high temperature;

[0028] (3) The shrinkage of the stress buffer layer above 600℃ makes the insulation layer fit tightly, and the carbonization products of aerogel fill the microcracks, avoiding the cracking failure caused by thermal expansion mismatch of traditional cables.

[0029] (4) After being directly quenched from 800℃ to 25℃, the cable showed no cracking or delamination, and the insulation resistance retention rate after thermal shock was >95%;

[0030] (5) The minimum bending radius is only 3 times the outer diameter of the cable, which is far superior to traditional ceramic / metal cables and facilitates installation in complex scenarios. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] Figure 1 This is a schematic diagram of the structure of the present invention.

[0033] Figure 2 This is a flowchart of the preparation process of the present invention. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] Figure 1 , Figure 2 The cable shown is resistant to high temperature of 800℃ and includes, from the inside out, a conductor layer 1, a first insulation layer 2, a stress buffer layer 3, a second insulation layer 4, and an outer sheath 5.

[0037] The conductor layer 1 is formed by twisting together oriented carbon nanotube fiber bundles, and the surface of the oriented carbon nanotube fiber bundles is coated with a boron nitride nano-coating with a thickness of 1-2 μm.

[0038] The first insulating layer 2 is a silicon carbide nanofiber felt impregnated with silica aerogel, with a density of 0.15-0.25 g / cm³. 3 Furthermore, a three-dimensional network structure is formed through electrospinning;

[0039] The stress buffer layer 3 is a composite film of a material with a negative thermal expansion coefficient and polysilane. The material with a negative thermal expansion coefficient is selected from at least one of ZrW2O8 or HfMo2O8.

[0040] The second insulating layer 4 is a composite felt of alumina aerogel and yttrium oxide-stabilized zirconium oxide fibers;

[0041] The outer sheath 5 is a carbon fiber woven sheath coated with SiC by chemical vapor deposition.

[0042] The diameter of a single carbon nanotube fiber bundle is 0.2-0.3 mm. Conductor layer 1 is formed by twisting 8-15 carbon nanotube fiber bundles together, and the diameter of conductor layer 1 after twisting is 1.2-1.8 mm.

[0043] The thickness of the first insulating layer 2 is 0.6-1.0 mm, and the thermal conductivity is ≤0.025 W / m·K; the thickness of the second insulating layer 4 is 1.0-1.5 mm, and the upper limit of temperature resistance is ≥1000℃.

[0044] The stress buffer layer 3 has a thickness of 0.08-0.12 mm and is a composite film that is pre-stretched by 10%-15% at 200-250℃ and then spirally wound around the first insulating layer 2.

[0045] The outer sheath 5 has a thickness of 0.2-0.4 mm, and the porosity of the carbon fiber braided sheath is ≤5% after being filled with SiC.

[0046] A central reinforcing core is provided on the inner side of the conductor layer 1, and a hollow arc-shaped extrusion cover is provided on the outer side of the central reinforcing core.

[0047] A method for preparing a high-temperature cable resistant to 800℃ includes the following steps:

[0048] S1: Preparation of conductor layer 1: Carbon nanotube fiber bundles are continuously prepared by floating catalyst method. The carbon nanotube fiber bundles are heat-treated at 950-1050℃ for 1-2 hours in an ammonia atmosphere to form a boron nitride nano-coating on their surface. Then, 8-15 bundles of the coated carbon nanotube fiber bundles are twisted together to obtain conductor layer 1.

[0049] S2: Preparation of the first insulating layer 2: Silicon carbide nanofiber felt is prepared by electrospinning, and silica aerogel precursor is infiltrated into the silicon carbide nanofiber felt by supercritical drying technology. After drying, the first insulating layer 2 is obtained; the first insulating layer 2 is coated on the conductor layer 1.

[0050] S3: Preparation of stress buffer layer 3: ZrW2O8 or HfMo2O8 is deposited on a polyimide film using magnetron sputtering technology, and then pyrolyzed to transform it into a composite film of a material with a negative thermal expansion coefficient and polycarbosilane; the composite film is pre-stretched by 10%-15% at 200-250℃, and then spirally wound around the first insulating layer 2 to form stress buffer layer 3;

[0051] S4: Preparation of the second insulating layer 4: Alumina aerogel precursor is infiltrated into yttrium oxide stabilized zirconia fiber felt, and the second insulating layer 4 is obtained after curing treatment; the second insulating layer 4 is wrapped around the stress buffer layer 3;

[0052] S5: Preparation of outer sheath 5: A carbon fiber braided sleeve is placed outside the second insulating layer 4. SiC is filled into the pores of the carbon fiber braided sleeve using a reactive melt infiltration process, and then densified by chemical vapor infiltration to form the outer sheath 5.

[0053] S6: Shaping treatment: The structure obtained in step S5 is kept at 300-400℃ for 2-3 hours in an inert atmosphere to obtain a high-temperature cable resistant to 800℃.

[0054] In step S2, the conditions for supercritical drying are: temperature 300-350℃, pressure 15-20MPa, and holding time 2-3h.

[0055] In step S5, the conditions for the reaction melt infiltration process are as follows: the molar ratio of Si powder to C powder as raw materials is 1:1.2, and the reaction is carried out in an argon atmosphere at 1500-1600℃ for 3-4 hours, so that SiC fills the pores of the carbon fiber braided sleeve.

[0056] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A high-temperature cable resistant to 800℃, characterized in that, From the inside out, it includes a conductor layer (1), a first insulating layer (2), a stress buffer layer (3), a second insulating layer (4), and an outer sheath (5); The conductor layer (1) is formed by twisting together oriented carbon nanotube fiber bundles, and the surface of the oriented carbon nanotube fiber bundles is coated with a boron nitride nano-coating with a thickness of 1-2 μm. The first insulating layer (2) is a silicon carbide nanofiber felt impregnated with silica aerogel, with a density of 0.15-0.25 g / cm³, and is formed into a three-dimensional network structure by electrospinning. The stress buffer layer (3) is a composite film of a material with a negative thermal expansion coefficient and polysilane, wherein the material with a negative thermal expansion coefficient is selected from at least one of ZrW2O8 or HfMo2O8; The second insulating layer (4) is a composite felt of alumina aerogel and yttrium oxide stabilized zirconium oxide fiber; The outer sheath (5) is a carbon fiber woven sheath coated with SiC by chemical vapor deposition.

2. The high-temperature cable resistant to 800℃ according to claim 1, characterized in that, The diameter of a single bundle of carbon nanotube fibers is 0.2-0.3 mm, and the conductor layer (1) is formed by twisting 8-15 bundles of carbon nanotube fibers together, and the diameter of the conductor layer (1) after twisting is 1.2-1.8 mm.

3. The high-temperature cable resistant to 800℃ according to claim 1, characterized in that, The thickness of the first insulating layer (2) is 0.6-1.0 mm and the thermal conductivity is ≤0.025 W / m·K; the thickness of the second insulating layer (4) is 1.0-1.5 mm and the upper limit of temperature resistance is ≥1000℃.

4. The high-temperature cable resistant to 800℃ according to claim 1, characterized in that, The stress buffer layer (3) has a thickness of 0.08-0.12 mm and is a composite film that is pre-stretched by 10%-15% at 200-250℃ and then spirally wound around the first insulating layer (2).

5. The high-temperature cable resistant to 800℃ according to claim 1, characterized in that, The outer sheath (5) has a thickness of 0.2-0.4 mm, and the porosity of the carbon fiber braided sheath is ≤5% after being filled with SiC.

6. The high-temperature cable resistant to 800℃ according to claim 1, characterized in that, A central reinforcing core is provided on the inner side of the conductor layer (1), and a hollow arc-shaped extrusion cover is provided on the outer side of the central reinforcing core.

7. A method for preparing a high-temperature cable resistant to 800℃, characterized in that, Includes the following steps: S1: Preparation of conductor layer (1): Carbon nanotube fiber bundles are continuously prepared by floating catalyst method. The carbon nanotube fiber bundles are heat-treated at 950-1050℃ for 1-2h in an ammonia atmosphere to form a boron nitride nano-coating on their surface. Then, 8-15 bundles of the coated carbon nanotube fiber bundles are twisted together to obtain conductor layer (1). S2: Preparation of the first insulating layer (2): Silicon carbide nanofiber felt is prepared by electrospinning, and silica aerogel precursor is infiltrated into the silicon carbide nanofiber felt by supercritical drying technology. After drying, the first insulating layer (2) is obtained; the first insulating layer (2) is wrapped around the conductor layer (1). S3: Preparation of stress buffer layer (3): ZrW2O8 or HfMo2O8 is deposited on polyimide film by magnetron sputtering, and then pyrolyzed to form a composite film of negative thermal expansion coefficient material and polycarbosilane; the composite film is pre-stretched by 10%-15% at 200-250℃, and then spirally wound around the first insulating layer (2) to form stress buffer layer (3). S4: Preparation of the second insulating layer (4): Alumina aerogel precursor is infiltrated into yttrium oxide stabilized zirconia fiber felt, and the second insulating layer (4) is obtained after curing treatment; the second insulating layer (4) is wrapped around the stress buffer layer (3); S5: Preparation of outer sheath (5): The carbon fiber braided sleeve is placed outside the second insulation layer (4), and SiC is filled into the pores of the carbon fiber braided sleeve by reactive melt infiltration process, and then densified by chemical vapor infiltration to form the outer sheath (5). S6: Shaping treatment: The structure obtained in step S5 is kept at 300-400℃ for 2-3 hours in an inert atmosphere to obtain a high-temperature cable resistant to 800℃.

8. The method for preparing a high-temperature cable resistant to 800℃ according to claim 7, characterized in that, In step S2, the conditions for supercritical drying are: temperature 300-350℃, pressure 15-20MPa, and holding time 2-3h.

9. The method for preparing a high-temperature cable resistant to 800℃ according to claim 7, characterized in that, In step S5, the conditions for the reaction melt infiltration process are as follows: the molar ratio of Si powder to C powder as raw materials is 1:1.2, and the reaction is carried out in an argon atmosphere at 1500-1600℃ for 3-4 hours, so that SiC fills the pores of the carbon fiber braided sleeve.

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