Composite submarine cable and manufacturing method thereof

Abstract

The present invention provides a composite submarine cable and a manufacturing method thereof, belonging to the technical field of submarine cables. The submarine cable comprises a cable core, a dynamic water-blocking layer, an intelligent sensing layer, a magnetic coding layer, an armor layer, and a self-healing outer sheath layer, which are arranged in sequence from the inside to the outside. The cable core comprises three power transmission units consisting of a copper alloy twisted conductor, a nano-modified insulation layer, and a semiconductor water-blocking shielding layer, and a central composite optical fiber unit containing a distributed optical fiber sensor. The present invention systematically solves the technical pain points of current submarine cables through the innovative integration of magnetic coding positioning, a dynamic water-blocking layer, intelligent sensing, and a bio-based self-healing outer sheath, providing core infrastructure support for future marine energy networks.

Description

Technical Field

[0001] The present invention belongs to the technical field of submarine cables, and in particular relates to a composite submarine cable and a manufacturing method thereof. Background Art

[0002] With the surge in global marine resource development and demand for offshore renewable energy transmission, submarine cables, as the core carriers of power transmission and information interconnection, face unprecedented challenges in terms of reliability, intelligence, and environmental adaptability. Despite years of development, traditional submarine cable technology still faces the following bottlenecks in the complex deep-sea environment:

[0003] Existing submarine cables rely on acoustic reflection or fluorescent markers for positioning. However, in water depths exceeding 3,000 meters or in turbid waters, acoustic signals are susceptible to interference from ocean current noise (attenuation >20dB / km). Fluorescent markers are obscured by multi-layer sheathing, resulting in visibility of less than 5 meters and positioning errors as high as ±5m. Furthermore, cable damage detection relies primarily on regular manual inspections or distributed temperature sensing (DTS), which cannot identify minor mechanical damage (such as cracks <5mm) in real time. This results in delayed fault response and an average repair cycle of up to 72 hours, posing a serious threat to power grid security.

[0004] Traditional water-blocking designs often use static water-blocking tape or potting compounds, which are susceptible to material creep under deep-sea high pressure (>30 MPa). The peel strength at the water-blocking tape joints can drop by >40%, leading to water seepage exceeding 2 meters per 24 hours (IEC 60502-2 standard limit of 0.5 meters). Some solutions have attempted to introduce metal sheaths (such as lead sheaths) to enhance mechanical strength, but this sacrifices cable flexibility. Bend fatigue in complex seabed terrain can easily cause sheath cracking, accelerating seawater infiltration.

[0005] The current mainstream outer sheath materials are polyethylene (PE) or polyvinyl chloride (PVC), which have a biodegradation rate of less than 5% (ASTM D5511). Discarded cables contribute to microplastic pollution in the ocean. Furthermore, traditional cables rely on periodic manual maintenance (such as replacing reflective strips and reinforcing armor layers), resulting in annual O&M costs of up to $100,000 per kilometer. Deep-sea operations also require specialized engineering vessels, further increasing the economic and environmental burden.

[0006] While some patents propose the concept of outer sheath self-repair, these rely on a single chemical curing mechanism, resulting in repair times exceeding two hours and a strength recovery rate of only 60%, which cannot meet the immediate repair requirements of deep-sea high-pressure environments. Furthermore, existing cables lack the ability to actively sense and locate damage, resulting in low repair efficiency.

[0007] Existing submarine cables have shortcomings in positioning accuracy, water resistance, intelligent self-repair, and environmental friendliness, making them difficult to meet the requirements of deep-sea seawater pressure (>60MPa), complex terrain, and stringent environmental regulations. A new technical solution combining high-precision positioning, adaptive water resistance, real-time damage response, and green materials is urgently needed to overcome the challenge of optimizing the reliability, cost-effectiveness, and environmental compatibility of deep-sea cables. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to propose a composite submarine cable and its manufacturing method. Through the innovative integration of magnetic coding positioning, dynamic water-blocking layer, intelligent sensing layer and bio-based self-healing outer sheath, it aims to systematically solve the above-mentioned technical pain points and provide core infrastructure support for future marine energy networks.

[0009] Specifically, the present invention provides a composite submarine cable, comprising a cable core, a dynamic water-blocking layer, an intelligent sensing layer, a magnetic coding layer, an armor layer, and a self-repairing outer sheath layer, which are arranged in sequence from the inside to the outside;

[0010] The cable core includes three power transmission units and a central composite optical fiber unit. The power transmission unit is composed of a conductor, a nano-modified insulation layer, and a semi-conductive water shielding layer. The central composite optical fiber unit contains distributed optical fiber sensors for real-time monitoring of temperature, strain, and micro-vibration.

[0011] The dynamic water-blocking layer is composed of hydrophobic nano-aerogel strips and shape memory polymer strips alternately wound in a spiral, and can adaptively adjust the porosity according to the external water pressure;

[0012] The smart sensing layer includes a piezoelectric ceramic array and a flexible graphene strain sensor, which is embedded in a silicone rubber matrix to monitor mechanical impact in real time and generate electrical signals;

[0013] The magnetic encoding layer comprises a flexible ferrite base tape and a surface-etched NdFeB magnetic domain array, which can encode optical cable information;

[0014] The armor layer is made of galvanized steel wires twisted together in a spiral and coated with an asphalt anti-corrosion layer on the surface;

[0015] The self-repairing outer sheath layer is formed by extrusion coating of bio-based polyurethane, and double-layer microcapsules are evenly dispersed in the outer sheath. After the microcapsules are broken, seawater infiltration triggers the resin to solidify and repair micro-damages.

[0016] Preferably, the conductor is a copper alloy stranded conductor with a cross-sectional area of ​​500-800 mm 2 The nano-modified insulating layer is a nano-Al2O3 modified polyethylene insulating layer with a thickness of 8~10mm. The central composite optical fiber unit is a distributed embedded temperature optical fiber sensor, strain optical fiber sensor and micro-motion optical fiber sensor based on 5G communication optical fiber.

[0017] Preferably, the porosity of the hydrophobic nano-aerogel tape is 80% to 90%, the compression rate of the aerogel is ≤15% when the water pressure changes, the glass transition temperature of the shape memory polymer is 30 to 40° C., and the expansion rate is 50% to 85%.

[0018] Preferably, the hydrophobic nanoaerogel tape is composited with silica aerogel and fluorinated carbon nanotubes, with a contact angle ≥150°, and the shape memory polymer has a shape recovery rate of 95% to 99%, and comprises a blend of polycaprolactone and polylactic acid, with a mass ratio of polycaprolactone to polylactic acid of 7:3.

[0019] Preferably, the flexible ferrite base tape of the magnetic coding layer is a Fe3O4 / SiO2 composite film with a thickness of 0.5mm~0.8mm and a tensile strength of 50MPa~80MPa. The magnetic domain direction of the magnetic coding layer is controlled by femtosecond laser programming to form a unique position ID. The magnetic domain spacing is 5mm and the coding density is 20 bits of binary information per meter.

[0020] Preferably, the gap filling rate of the galvanized steel wires of the armor layer is 90%, and an insulating buffer layer is provided between the armor layer and the magnetic encoding layer, with a thickness of 1 to 3 mm.

[0021] Preferably, the particle size of the double-layer microcapsules is 80-150 μm, the inner wall material is polyurethane-acrylic acid copolymer, the outer wall material is sodium alginate-chitosan cross-linked network, and the mass ratio of the inner wall material to the outer wall material is 3:1.

[0022] The present invention also provides a method for manufacturing the composite submarine cable, comprising the following steps:

[0023] S1: The conductor is drawn through 12 passes to the target cross-sectional area. After surface cleaning, it is coated with a nano-modified insulation layer and a semi-conductive water shielding layer through a three-layer co-extrusion process to prepare a power transmission unit. Three power transmission units are twisted into a central composite optical fiber unit in the middle to form a cable with a pitch ratio of 12-15:1.

[0024] S2: The hydrophobic nano-aerogel tape and the shape memory polymer tape were alternately wrapped at a 30° spiral angle with an overlap rate of 15%, and then subjected to a hot air treatment at 80°C for 20 minutes to melt-bond the shape memory polymer tape and the hydrophobic nano-aerogel tape at the interface, with an interfacial peel strength of not less than 1.5 N / mm, to form a dynamic water-blocking layer;

[0025] S3: Piezoelectric ceramic sheets of a specific size and flexible graphene strain sensors are embedded in a silicone rubber strip at a specific spacing. The strip is then wrapped around the dynamic water barrier layer at a 45° winding angle. After vacuum vulcanization, an intelligent sensing layer is formed.

[0026] S4: Use magnetron sputtering to deposit a 50μm thick NdFeB film on the ferrite substrate. Femtosecond laser etching is used to etch the magnetic domain direction to generate binary position code. The magnetic domain coding tape is covered with the smart sensing layer in a 0° longitudinal manner. The tension is controlled at 15N~25N to form a magnetic coding layer.

[0027] S5: Silicone rubber is extruded and coated on the outside of the magnetic coding layer to form an insulating buffer layer. The galvanized steel wire is twisted in a left-hand twisting manner with a twist angle of 80°. An asphalt anti-corrosion layer is applied on the surface and dried to prepare the armor layer.

[0028] S6: Add double-layer microcapsules to bio-based polyurethane, add 10wt.% flame retardant and mix thoroughly. Then, coat it on the outside of the armor layer through an extrusion process to prepare a self-repairing outer sheath layer.

[0029] Preferably, the piezoelectric ceramic sheet of specific size in step S3 is 5 mm×5 mm×0.5 mm, the vacuum vulcanization process is vacuum vulcanization at 120°C and 0.5 MPa for 30 minutes, the specific spacing is 1 m~30 m, and the mold temperature of the extrusion process in step S6 is 175°C~185°C, and the pressure is 12~18 MPa.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The present invention achieves high-precision positioning and strong resistance to environmental interference of submarine cables by setting up a magnetic coding layer. The unique cable ID information carried by the magnetic coding layer can be monitored by low-frequency electromagnetic decoding technology to achieve precise positioning, which far exceeds traditional acoustic positioning and fluorescent reflection search positioning. It has strong information penetration and can avoid underwater acoustic frequency band and power frequency interference. It can work stably in turbid waters and strong ocean current environments, and can accurately reflect the detailed information of each section of optical cable, facilitating the accurate identification of the damaged cable location.

[0032] (2) The self-repairing outer sheath contains double-layer microcapsules. When the outer sheath is slightly damaged, the microcapsules rupture and the seawater infiltration triggers the resin to automatically solidify. The micro-damage can be automatically repaired within 30 minutes, preventing the damaged area from further deteriorating in the harsh environment of the deep sea.

[0033] (3) Through the piezoelectric ceramics and graphene sensors in the intelligent sensing layer, combined with the temperature, strain and micro-motion optical fiber sensor data in the cable core, the abnormal status of the cable can be monitored quickly and in real time. Combined with the magnetic coding layer for position information positioning, it is convenient for underwater robots to quickly reach the abnormal location and carry out necessary inspections and repairs.

[0034] (4) After the cable is accidentally damaged and cracked, due to the change in seawater pressure at the rupture point, the cable's dynamic water-blocking layer can adaptively adjust the internal pores according to the pressure change, maintain the cable's dynamic water-blocking shape, and prevent the cable core from being further eroded by seawater.

[0035] (5) The introduction of bio-based polyurethane into the outer sheath layer is not only more environmentally friendly than the traditional PE / lead sheath, but also effectively reduces carbon emissions during production and preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 Schematic cross-sectional view of the cable of the present invention.

[0038] The numbers in the accompanying drawings are: cable core 1, power transmission unit 1-1, conductor 1-1-1, nano-modified insulation layer 1-1-2, semiconductor water-resistant shielding layer 1-1-3, central composite optical fiber unit 1-2, dynamic water-resistant layer 2, intelligent sensing layer 3, piezoelectric ceramic sheet 3-1, flexible graphene strain sensor 3-2, magnetic coding layer 4, insulating buffer layer 5, armor layer 6, self-repairing outer sheath layer 7. DETAILED DESCRIPTION

[0039] The following examples are intended to illustrate the present invention but are not intended to limit the scope of the present invention. Modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and substance of the present invention are intended to fall within the scope of the present invention. Unless otherwise specified, the techniques used in the examples are conventional means well known to those skilled in the art.

[0040] Example 1

[0041] like Figure 1 The composite submarine cable shown includes a cable core 1, a dynamic water-blocking layer 2, an intelligent sensing layer 3, a magnetic coding layer 4, an insulating buffer layer 5, an armor layer 6, and a self-repairing outer sheath layer 7, which are arranged in sequence from the inside to the outside. The cable core 1 includes three power transmission units 1-1 and a central composite optical fiber unit 1-2. The power transmission unit is composed of a conductor 1-1-1, a nano-modified insulating layer 1-1-2, and a semi-conductive water-blocking shielding layer 1-1-3. The conductor 1-1-1 is a copper alloy stranded conductor with a cross-sectional area of ​​500mm. 2The nano-modified insulating layer 1-1-2 is a nano-Al2O3 modified polyethylene insulating layer with a thickness of 8mm. The central composite optical fiber unit 1-2 is a distributed embedded temperature optical fiber sensor, strain optical fiber sensor and micro-motion optical fiber sensor based on the 5G communication optical fiber, which is used to monitor temperature, strain and micro-vibration in real time. The dynamic water-blocking layer 2 is composed of hydrophobic nano-aerogel tape and shape memory polymer tape alternately wound in a spiral. The hydrophobic nano-aerogel tape is a composite of silica aerogel and fluorinated carbon nanotubes with a contact angle of 150° and hydrophobicity. The porosity of the nano-aerogel tape is 80%, the compression rate of the aerogel is 15% when the water pressure changes, the glass transition temperature of the shape memory polymer is 30 ° C, the expansion rate is 50%, and the shape recovery rate of the shape memory polymer is 95%. It contains a blend of polycaprolactone and polylactic acid, and the mass ratio of polycaprolactone to polylactic acid is 7:3. The dynamic water-blocking layer 2 can adaptively adjust the porosity according to the external water pressure; the intelligent sensing layer 3 includes a piezoelectric ceramic array 3-1 and a flexible graphene strain sensor 3-2. The size of the piezoelectric ceramic sheet 3-1 is 5 mm × 5 mm×0.5mm, and the two are embedded in the silicone rubber matrix at a distance of 1m to monitor mechanical impact in real time and generate electrical signals; the magnetic coding layer 4 includes a flexible ferrite base tape and a surface-etched NdFeB magnetic domain array, which can encode optical cable information. The flexible ferrite base tape of the magnetic coding layer 4 is a Fe3O4 / SiO2 composite film with a thickness of 0.5mm and a tensile strength of 50MPa. The magnetic domain direction of the magnetic coding layer is controlled by femtosecond laser programming to form a unique position ID. The magnetic domain spacing is 5mm and the coding density is 20 bits of binary information per meter; the armor layer 6 is a galvanized steel wire spiral The armor layer 6 is twisted and coated with an asphalt anti-corrosion layer on the surface. The gap filling rate of the galvanized steel wire in the armor layer 6 is 90%; an insulating buffer layer 5 with a thickness of 1 mm is provided between the armor layer 6 and the magnetic coding layer 4; the self-repairing outer sheath layer 7 is made of bio-based polyurethane extrusion coating, and double-layer microcapsules are evenly dispersed in the outer sheath. The particle size of the double-layer microcapsules is 80 μm, the inner wall material is polyurethane-acrylic acid copolymer, and the outer wall material is sodium alginate-chitosan cross-linked network. The mass ratio of the inner wall material to the outer wall material is 3:1. After the microcapsules are ruptured, the seawater penetration triggers the resin to cure and repair the micro-damage.

[0042] A specific method for manufacturing a composite submarine cable includes the following steps:

[0043] S1: The conductor 1-1-1 is drawn through 12 passes to the target cross-sectional area. After the surface is cleaned, it is coated with a nano-modified insulation layer 1-1-2 and a semi-conductive water shielding layer 1-1-3 through a three-layer co-extrusion process to prepare a power transmission unit 1-1. Three power transmission units 1-1 and a central composite optical fiber unit 1-2 in the middle are stranded into a cable core 1 with a pitch ratio of 12:1.

[0044] S2: The hydrophobic nano-aerogel tape and the shape memory polymer tape were alternately wrapped at a 30° spiral angle with an overlap ratio of 15%, and then subjected to a hot air treatment at 80°C for 20 minutes to melt-bond the shape memory polymer tape and the hydrophobic nano-aerogel tape at the interface, with an interfacial peel strength of not less than 1.5 N / mm, to form a dynamic water-blocking layer 2;

[0045] S3: A piezoelectric ceramic sheet 3-1 and a flexible graphene strain sensor 3-2 with a size of 5 mm × 5 mm × 0.5 mm were embedded in a silicone rubber tape at a spacing of 1 m. The strip was wrapped around the dynamic water barrier layer at a 45° winding angle and vacuum vulcanized at 120°C and 0.5 MPa for 30 min to form the smart sensing layer 3.

[0046] S4: Using magnetron sputtering to deposit a 50 μm thick NdFeB film on the ferrite substrate, femtosecond laser etching the magnetic domain direction to generate binary position coding, and then covering the smart sensing layer 4 with the magnetic domain coding tape in a 0° longitudinal direction with a tension controlled at 15 N to form a magnetic coding layer 4;

[0047] S5: Silicone rubber is extruded and coated on the outside of the magnetic coding layer 4 to form an insulating buffer layer 5, galvanized steel wire is twisted in a left-hand twisting manner with a twist angle of 80°, an asphalt anti-corrosion layer is applied on the surface, and after drying, an armor layer 6 is prepared;

[0048] S6: Add double-layer microcapsules to bio-based polyurethane, add 10wt.% of flame retardant and mix thoroughly, then coat it on the outside of the armor layer through an extrusion process. The mold temperature of the extrusion process is 175°C and the pressure is 12MPa to prepare a self-repairing outer sheath layer 7.

[0049] Example 2

[0050] like Figure 1 The composite submarine cable shown includes a cable core 1, a dynamic water-blocking layer 2, an intelligent sensing layer 3, a magnetic coding layer 4, an insulating buffer layer 5, an armor layer 6, and a self-repairing outer sheath layer 7, which are arranged in sequence from the inside to the outside. The cable core 1 includes three power transmission units 1-1 and a central composite optical fiber unit 1-2. The power transmission unit is composed of a conductor 1-1-1, a nano-modified insulating layer 1-1-2, and a semi-conductive water-blocking shielding layer 1-1-3. The conductor 1-1-1 is a copper alloy stranded conductor with a cross-sectional area of ​​650mm. 2The nano-modified insulating layer 1-1-2 is a nano-Al2O3 modified polyethylene insulating layer with a thickness of 9mm. The central composite optical fiber unit 1-2 is a distributed embedded temperature optical fiber sensor, strain optical fiber sensor and micro-motion optical fiber sensor based on the 5G communication optical fiber, which is used to monitor temperature, strain and micro-vibration in real time. The dynamic water-blocking layer 2 is composed of hydrophobic nano-aerogel tape and shape memory polymer tape alternately wound in a spiral. The hydrophobic nano-aerogel tape is a composite of silica aerogel and fluorinated carbon nanotubes with a contact angle of 160°. The porosity of the nano-aerogel tape is 85%, the compression rate of the aerogel is 12% when the water pressure changes, the glass transition temperature of the shape memory polymer is 35 ° C, the expansion rate is 68%, and the shape recovery rate of the shape memory polymer is 97%. It contains a blend of polycaprolactone and polylactic acid, and the mass ratio of polycaprolactone to polylactic acid is 7:3. The dynamic water-blocking layer 2 can adaptively adjust the porosity according to the external water pressure; the intelligent sensing layer 3 includes a piezoelectric ceramic array 3-1 and a flexible graphene strain sensor 3-2. The size of the piezoelectric ceramic sheet 3-1 is 5 mm × 5 mm×0.5mm, and the two are embedded in the silicone rubber matrix at a distance of 10m to monitor mechanical impact in real time and generate electrical signals; the magnetic coding layer 4 includes a flexible ferrite base tape and a surface-etched NdFeB magnetic domain array, which can encode optical cable information. The flexible ferrite base tape of the magnetic coding layer 4 is a Fe3O4 / SiO2 composite film with a thickness of 0.65mm and a tensile strength of 65MPa. The magnetic domain direction of the magnetic coding layer is controlled by femtosecond laser programming to form a unique position ID. The magnetic domain spacing is 5mm and the coding density is 20 bits of binary information per meter; the armor layer 6 is a galvanized steel wire screw The armor layer 6 is twisted and coated with an asphalt anti-corrosion layer. The gap filling rate of the galvanized steel wire in the armor layer 6 is 90%; an insulating buffer layer 5 with a thickness of 2 mm is provided between the armor layer 6 and the magnetic coding layer 4; the self-repairing outer sheath layer 7 is made of bio-based polyurethane extrusion coating, and double-layer microcapsules are evenly dispersed in the outer sheath. The particle size of the double-layer microcapsules is 115 μm, the inner wall material is polyurethane-acrylic acid copolymer, and the outer wall material is sodium alginate-chitosan cross-linked network. The mass ratio of the inner wall material to the outer wall material is 3:1. After the microcapsules are ruptured, the resin is cured and repaired by seawater penetration.

[0051] A specific method for manufacturing a composite submarine cable includes the following steps:

[0052] S1: The conductor 1-1-1 is drawn through 12 passes to the target cross-sectional area. After the surface is cleaned, it is coated with a nano-modified insulation layer 1-1-2 and a semi-conductive water shielding layer 1-1-3 through a three-layer co-extrusion process to prepare a power transmission unit 1-1. Three power transmission units 1-1 and a central composite optical fiber unit 1-2 in the middle are stranded into a cable core 1 with a pitch ratio of 13.5:1.

[0053] S2: The hydrophobic nano-aerogel tape and the shape memory polymer tape were alternately wrapped at a 30° spiral angle with an overlap ratio of 15%, and then subjected to a hot air treatment at 80°C for 20 minutes to melt-bond the shape memory polymer tape and the hydrophobic nano-aerogel tape at the interface, with an interfacial peel strength of not less than 1.5 N / mm, to form a dynamic water-blocking layer 2;

[0054] S3: A piezoelectric ceramic sheet 3-1 and a flexible graphene strain sensor 3-2 with a size of 5 mm × 5 mm × 0.5 mm were embedded in a silicone rubber tape at a spacing of 15 μm. The strip was wrapped around the dynamic water barrier layer at a 45° winding angle and then vacuum vulcanized at 120°C and 0.5 MPa for 30 min to form the smart sensing layer 3.

[0055] S4: Using magnetron sputtering to deposit a 50 μm thick NdFeB film on the ferrite substrate, femtosecond laser etching the magnetic domain direction to generate binary position coding, and then covering the smart sensing layer 4 with the magnetic domain coding tape in a 0° longitudinal direction with a tension controlled at 20 N to form a magnetic coding layer 4;

[0056] S5: Silicone rubber is extruded and coated on the outside of the magnetic coding layer 4 to form an insulating buffer layer 5, galvanized steel wire is twisted in a left-hand twisting manner with a twist angle of 80°, an asphalt anti-corrosion layer is applied on the surface, and after drying, an armor layer 6 is prepared;

[0057] S6: Add double-layer microcapsules to bio-based polyurethane, add 10wt.% of flame retardant and mix thoroughly, then coat it on the outside of the armor layer through an extrusion process. The mold temperature of the extrusion process is 180°C and the pressure is 15MPa to prepare a self-repairing outer sheath layer 7.

[0058] Example 3

[0059] like Figure 1 The composite submarine cable shown includes a cable core 1, a dynamic water-blocking layer 2, an intelligent sensing layer 3, a magnetic coding layer 4, an insulating buffer layer 5, an armor layer 6, and a self-repairing outer sheath layer 7, which are arranged in sequence from the inside to the outside. The cable core 1 includes three power transmission units 1-1 and a central composite optical fiber unit 1-2. The power transmission unit is composed of a conductor 1-1-1, a nano-modified insulating layer 1-1-2, and a semi-conductive water-blocking shielding layer 1-1-3. The conductor 1-1-1 is a copper alloy stranded conductor with a cross-sectional area of ​​800mm. 2The nano-modified insulating layer 1-1-2 is a nano-Al2O3 modified polyethylene insulating layer with a thickness of 10 mm. The central composite optical fiber unit 1-2 is a distributed embedded temperature optical fiber sensor, strain optical fiber sensor and micro-motion optical fiber sensor based on the 5G communication optical fiber, which is used to monitor temperature, strain and micro-vibration in real time. The dynamic water-blocking layer 2 is composed of hydrophobic nano-aerogel tape and shape memory polymer tape alternately wound in a spiral. The hydrophobic nano-aerogel tape is a composite of silica aerogel and fluorinated carbon nanotubes with a contact angle of 165° and hydrophobicity. The porosity of the nano-aerogel tape is 90%, the compression rate of the aerogel is 12% when the water pressure changes, the glass transition temperature of the shape memory polymer is 40 ° C, the expansion rate is 85%, and the shape recovery rate of the shape memory polymer is 99%. It contains a blend of polycaprolactone and polylactic acid, and the mass ratio of polycaprolactone to polylactic acid is 7:3. The dynamic water-blocking layer 2 can adaptively adjust the porosity according to the external water pressure; the intelligent sensing layer 3 includes a piezoelectric ceramic array 3-1 and a flexible graphene strain sensor 3-2. The size of the piezoelectric ceramic sheet 3-1 is 5 mm × 5 mm×0.5mm, and the two are embedded in the silicone rubber matrix at a spacing of 30m to monitor mechanical impact in real time and generate electrical signals; the magnetic coding layer 4 includes a flexible ferrite base tape and a surface-etched NdFeB magnetic domain array, which can encode optical cable information. The flexible ferrite base tape of the magnetic coding layer 4 is a Fe3O4 / SiO2 composite film with a thickness of 0.8mm and a tensile strength of 80MPa. The magnetic domain direction of the magnetic coding layer is controlled by femtosecond laser programming to form a unique position ID. The magnetic domain spacing is 5mm and the coding density is 20 bits of binary information per meter; the armor layer 6 is a galvanized steel wire spiral The armor layer 6 is twisted and coated with an asphalt anti-corrosion layer on the surface. The gap filling rate of the galvanized steel wire in the armor layer 6 is 90%; an insulating buffer layer 5 with a thickness of 3 mm is provided between the armor layer 6 and the magnetic coding layer 4; the self-repairing outer sheath layer 7 is made of bio-based polyurethane extrusion coating, and double-layer microcapsules are evenly dispersed in the outer sheath. The particle size of the double-layer microcapsules is 150 μm, the inner wall material is polyurethane-acrylic acid copolymer, and the outer wall material is sodium alginate-chitosan cross-linked network. The mass ratio of the inner wall material to the outer wall material is 3:1. After the microcapsules are ruptured, the seawater penetration triggers the resin to cure and repair the micro-damage.

[0060] A specific method for manufacturing a composite submarine cable includes the following steps:

[0061] S1: The conductor 1-1-1 is drawn through 12 passes to the target cross-sectional area. After the surface is cleaned, it is coated with a nano-modified insulation layer 1-1-2 and a semi-conductive water shielding layer 1-1-3 through a three-layer co-extrusion process to prepare a power transmission unit 1-1. Three power transmission units 1-1 and a central composite optical fiber unit 1-2 in the middle are stranded to form a cable core 1 with a pitch ratio of 15:1.

[0062] S2: The hydrophobic nano-aerogel tape and the shape memory polymer tape were alternately wrapped at a 30° spiral angle with an overlap ratio of 15%, and then subjected to a hot air treatment at 80°C for 20 minutes to melt-bond the shape memory polymer tape and the hydrophobic nano-aerogel tape at the interface, with an interfacial peel strength of not less than 1.5 N / mm, to form a dynamic water-blocking layer 2;

[0063] S3: A piezoelectric ceramic sheet 3-1 with a size of 5 mm × 5 mm × 0.5 mm and a flexible graphene strain sensor 3-2 were embedded in a silicone rubber tape at a spacing of 30 μm. The strip was wrapped around the dynamic water barrier layer at a 45° winding angle and then vacuum vulcanized at 120°C and 0.5 MPa for 30 min to form the smart sensing layer 3.

[0064] S4: NdFeB thin film with a thickness of 50 μm is deposited on the ferrite substrate by magnetron sputtering. The magnetic domain direction is etched by femtosecond laser to generate binary position code. The magnetic domain coding tape is covered with the smart sensing layer 4 in a 0° longitudinal manner. The tension is controlled at 25N to form the magnetic coding layer 4.

[0065] S5: Silicone rubber is extruded and coated on the outside of the magnetic coding layer 4 to form an insulating buffer layer 5, galvanized steel wire is twisted in a left-hand twisting manner with a twist angle of 80°, an asphalt anti-corrosion layer is applied on the surface, and after drying, an armor layer 6 is prepared;

[0066] S6: Add double-layer microcapsules to bio-based polyurethane, add 10wt.% of flame retardant and mix thoroughly, then coat it on the outside of the armor layer through an extrusion process. The mold temperature of the extrusion process is 185°C and the pressure is 18MPa to prepare a self-repairing outer sheath layer 7.

[0067] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A composite submarine cable, characterized in that: The cable comprises a cable core, a dynamic water-blocking layer, an intelligent sensing layer, a magnetic coding layer, an armor layer, and a self-repairing outer sheath layer, which are arranged in sequence from the inside to the outside; The cable core includes three power transmission units and a central composite optical fiber unit, wherein the power transmission unit is composed of a conductor, a nano-modified insulation layer, and a semi-conductive water shielding layer, and the central composite optical fiber unit contains a distributed optical fiber sensor; The dynamic water-blocking layer is composed of hydrophobic nano-aerogel strips and shape memory polymer strips alternately wound in a spiral; The smart sensing layer comprises a piezoelectric ceramic array and a flexible graphene strain sensor, which are embedded in a silicone rubber matrix; The magnetic encoding layer comprises a flexible ferrite base tape and a surface-etched NdFeB magnetic domain array to encode optical cable information; The armor layer is made of galvanized steel wires twisted together in a spiral and coated with an asphalt anti-corrosion layer on the surface; The self-repairing outer sheath layer is formed by extrusion and coating of bio-based polyurethane, and double-layer microcapsules are evenly dispersed in the outer sheath.

2. The composite submarine cable according to claim 1, characterized in that The conductor is a copper alloy stranded conductor with a cross-sectional area of ​​500~800mm 2 The nano-modified insulating layer is a nano-Al2O3 modified polyethylene insulating layer with a thickness of 8~10mm. The central composite optical fiber unit is a distributed embedded temperature optical fiber sensor, strain optical fiber sensor and micro-motion optical fiber sensor based on 5G communication optical fiber.

3. The composite submarine cable according to claim 1, characterized in that The porosity of the hydrophobic nano-aerogel tape is 80% to 90%, and the compression rate of the aerogel is ≤15% when the water pressure changes. The glass transition temperature of the shape memory polymer is 30 to 40° C., and the expansion rate is 50% to 85%.

4. The composite submarine cable according to claim 1, characterized in that The hydrophobic nanoaerogel tape is composed of a composite of silica aerogel and fluorinated carbon nanotubes, with a contact angle of ≥150°. The shape recovery rate of the shape memory polymer is 95% to 99%, and it contains a blend of polycaprolactone and polylactic acid, with a mass ratio of polycaprolactone to polylactic acid of 7:

3.

5. The composite submarine cable according to claim 1, characterized in that The flexible ferrite base tape of the magnetic coding layer is a Fe3O4 / SiO2 composite film with a thickness of 0.5mm~0.8mm and a tensile strength of 50MPa~80MPa. The magnetic domain direction of the magnetic coding layer is controlled by femtosecond laser programming to form a unique position ID. The magnetic domain spacing is 5mm and the coding density is 20 bits of binary information per meter.

6. The composite submarine cable according to claim 1, characterized in that The gap filling rate of the galvanized steel wires in the armor layer is 90%, and an insulating buffer layer is provided between the armor layer and the magnetic encoding layer, with a thickness of 1 to 3 mm.

7. The composite submarine cable according to claim 1, characterized in that The particle size of the double-layer microcapsule is 80-150 μm, the inner wall material is polyurethane-acrylic acid copolymer, the outer wall material is sodium alginate-chitosan cross-linked network, and the mass ratio of the inner wall material to the outer wall material is 3:

1.

8. A method for preparing a composite submarine cable according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: S1: The conductor is drawn through 12 passes to the target cross-sectional area. After surface cleaning, it is coated with a nano-modified insulation layer and a semi-conductive water shielding layer through a three-layer co-extrusion process to prepare a power transmission unit. Three power transmission units are twisted into a central composite optical fiber unit in the middle to form a cable with a pitch ratio of 12-15:

1. S2: The hydrophobic nano-aerogel tape and the shape memory polymer tape were alternately wrapped at a 30° spiral angle with an overlap rate of 15%, and then subjected to a hot air treatment at 80°C for 20 minutes to melt-bond the shape memory polymer tape and the hydrophobic nano-aerogel tape at the interface, with an interfacial peel strength of not less than 1.5 N / mm, to form a dynamic water-blocking layer; S3: Piezoelectric ceramic sheets of a specific size and flexible graphene strain sensors are embedded in a silicone rubber strip at a specific spacing. The strip is then wrapped around the dynamic water barrier layer at a 45° winding angle. After vacuum vulcanization, an intelligent sensing layer is formed. S4: Use magnetron sputtering to deposit a 50μm thick NdFeB film on the ferrite substrate. Femtosecond laser etching is used to etch the magnetic domain direction to generate binary position code. The magnetic domain coding tape is covered with the smart sensing layer in a 0° longitudinal manner. The tension is controlled at 15N~25N to form a magnetic coding layer. S5: Silicone rubber is extruded and coated on the outside of the magnetic coding layer to form an insulating buffer layer. The galvanized steel wire is twisted in a left-hand twisting manner with a twist angle of 80°. An asphalt anti-corrosion layer is applied on the surface and dried to prepare the armor layer. S6: Add double-layer microcapsules to bio-based polyurethane, add 10wt.% flame retardant and mix thoroughly. Then, coat it on the outside of the armor layer through an extrusion process to prepare a self-repairing outer sheath layer.

9. The method for preparing a composite submarine cable according to claim 8, characterized in that: The specific size of the piezoelectric ceramic piece in step S3 is 5 mm×5 mm×0.5 mm, the vacuum vulcanization process is vacuum vulcanization at 120° C. and 0.5 MPa for 30 minutes, and the specific spacing is 1 m to 30 m.

10. The method for preparing a composite submarine cable according to claim 8, characterized in that: The mold temperature of the extrusion process in step S6 is 175° C. to 185° C., and the pressure is 12 to 18 MPa.

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