Silicon carbide fiber composite core wire and method of manufacture

Abstract

The application relates to the technical field of composite materials, and particularly relates to a silicon carbide fiber composite core wire and a preparation method. Dimethyldichlorosilane is obtained to carry out dechlorination polymerization, polydimethylsilane is generated, high-temperature and high-pressure cracking rearrangement is carried out, and polycarbosilane is obtained; the polycarbosilane is melted and extruded through a spinning hole to obtain continuous polycarbosilane original fibers, the continuous polycarbosilane original fibers are crosslinked to obtain crosslinked fibers, high-temperature cracking is carried out, and the crosslinked fibers are converted into inorganic silicon carbide fiber bundles; the silicon carbide fiber bundles are immersed in a high-temperature resistant resin glue solution and enter a heated pultrusion mold to be pultruded into a silicon carbide fiber composite core rod; inner layer aluminum wires are twisted outside the silicon carbide fiber composite core rod, and outer layer aluminum wires are twisted outside the inner layer aluminum wires to obtain the silicon carbide fiber composite core wire. The prepared composite core wire has the outstanding advantages of high strength, high modulus, high-temperature resistance, oxidation resistance, corrosion resistance, a low thermal expansion coefficient and large conveying capacity, and has important economic benefits in power transmission line capacity increasing and reconstruction projects.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a silicon carbide fiber composite core conductor and its preparation method. Background Technology

[0002] Currently, overhead transmission lines widely use steel-cored aluminum stranded wire, aluminum-clad steel core conductors, and carbon fiber composite core conductors. These have significant technical defects in scenarios such as high temperature, heavy load, long distance, and capacity expansion, and can no longer meet the development needs of power grids for large capacity, high temperature resistance, long life, and lightweight design.

[0003] Conventional steel-cored aluminum stranded wires, using a steel core as the reinforcing component, suffer from problems such as high density, heavy weight, high coefficient of thermal expansion, and poor temperature resistance. Their long-term operating temperature typically does not exceed 70℃. Under high-temperature conditions, creep and increased sag easily occur, leading to insufficient safe distances and limiting current carrying capacity. Simultaneously, the steel and aluminum are prone to electrochemical corrosion, accelerating conductor aging, shortening service life, and increasing line maintenance costs. While aluminum-clad steel core conductors offer some improvement in corrosion resistance, the fundamental problems of heavy weight and limited temperature resistance remain unresolved. Summary of the Invention

[0004] The purpose of this invention is to provide a silicon carbide fiber composite core conductor and its preparation method, which solves the problems of large weight and limited temperature resistance of existing overhead conductors.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a silicon carbide fiber composite core conductor, comprising the following steps: Dimethyldichlorosilane raw material is obtained and subjected to dechlorination polymerization to generate polydimethylsilane. The polydimethylsilane is then subjected to high-temperature and high-pressure pyrolysis and rearrangement to obtain polycarbosilane. The polycarbosilane is melted and extruded through a spinneret to obtain continuous polycarbosilane fibrils, and the continuous polycarbosilane fibrils are crosslinked to obtain crosslinked fibers; Under high-purity inert gas conditions, the cross-linked fibers are subjected to high-temperature pyrolysis to transform them into inorganic silicon carbide fiber bundles. The silicon carbide fiber bundles are fully impregnated with high-temperature resistant resin liquid, and then enter a heated pultrusion mold to be continuously pultruded into silicon carbide fiber composite mandrels. The inner aluminum wire is stranded around the silicon carbide fiber composite core rod, and then the outer aluminum wire is stranded around the inner aluminum wire to obtain a silicon carbide fiber composite core conductor.

[0006] The specific method for obtaining dimethyldichlorosilane raw material through dechlorination polymerization to generate polydimethylsilane, and then subjecting the polydimethylsilane to high-temperature and high-pressure pyrolysis and rearrangement to obtain polycarbosilane is as follows: Dimethyldichlorosilane was used as a raw material and subjected to a dechlorination polymerization reaction under an inert atmosphere to produce polydimethylsilane. The polydimethylsilane was placed in a high-pressure reactor and subjected to high-temperature and high-pressure pyrolysis and rearrangement at 350℃~450℃ and 1.5MPa~3.0MPa for 8h~16h to obtain the rearranged product. The rearranged product was cooled, purified by vacuum distillation, and polycarbosilane was obtained.

[0007] The continuous polycarbosilane fibrils are crosslinked by oxidative crosslinking or by electron beam / ultraviolet irradiation crosslinking in an oxygen-free atmosphere, and the chemical crosslinking is carried out by holding the fibers at 200°C in an air atmosphere for 1 to 3 hours.

[0008] The cross-linked fibers are subjected to high-temperature pyrolysis by introducing high-purity inert gas and heating to 1200℃~1400℃ at a rate of 5℃ / min~15℃ / min, and holding at that temperature for 1h~3h.

[0009] The temperature of the impregnating high-temperature resistant resin solution is 40℃~80℃, and the resin content is 20wt%~40wt%.

[0010] The pultrusion speed is 0.5 m / min to 3 m / min.

[0011] In a second aspect, the present invention also provides a silicon carbide fiber composite core conductor, which is prepared by the silicon carbide fiber composite core conductor preparation method as described in the first aspect above, comprising silicon carbide fiber, resin layer, inner aluminum wire and outer aluminum wire, wherein the resin layer is disposed on the outside of the silicon carbide fiber, the inner aluminum wire is stranded on the side of the resin layer away from the silicon carbide fiber, and the outer aluminum wire is stranded on the side of the inner aluminum wire away from the resin layer.

[0012] This invention discloses a method for preparing silicon carbide fiber composite core conductors. The method involves obtaining dimethyldichlorosilane as a raw material, performing dechlorination polymerization to generate polydimethylsilane, and then subjecting the polydimethylsilane to high-temperature, high-pressure pyrolysis and rearrangement to obtain polycarbosilane. The polycarbosilane is melted and extruded through a spinneret to obtain continuous polycarbosilane protofibrils. These continuous polycarbosilane protofibrils are then crosslinked to obtain crosslinked fibers. Under high-purity inert gas conditions, the crosslinked fibers are subjected to high-temperature pyrolysis to transform them into inorganic silicon carbide fiber bundles. The silicon carbide fiber bundles are then thoroughly impregnated with a durable, heat-resistant polymer. High-temperature resin molten material is then fed into a heated pultrusion mold and continuously pultruded into a silicon carbide fiber composite core rod. An inner layer of aluminum wire is stranded around the silicon carbide fiber composite core rod, and then an outer layer of aluminum wire is stranded around the inner layer of aluminum wire to obtain a silicon carbide fiber composite core conductor. The composite core conductor prepared by this method has outstanding advantages such as high strength, high modulus, high temperature resistance, oxidation resistance, corrosion resistance, low coefficient of thermal expansion, and large transmission capacity. It has significant economic benefits in power transmission line capacity expansion and renovation projects, thus solving the problems of large weight and limited temperature resistance of existing overhead conductors. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0014] Figure 1 This is a flowchart of a method for preparing a silicon carbide fiber composite core conductor provided by the present invention.

[0015] Figure 2 This is a schematic diagram illustrating a specific method for obtaining polydimethylsilane by dechlorinating and polymerizing dimethyldichlorosilane raw material to generate polydimethylsilane, and then subjecting the polydimethylsilane to high-temperature and high-pressure pyrolysis and rearrangement to obtain polycarbosilane.

[0016] Figure 3 This is a schematic diagram of a silicon carbide fiber composite core conductor provided by the present invention.

[0017] In the diagram: 1-Silicon carbide fiber, 2-Resin layer, 3-Inner aluminum wire, 4-Outer aluminum wire. Detailed Implementation

[0018] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0019] Please see Figures 1 to 2 In a first aspect, the present invention provides a method for preparing a silicon carbide fiber composite core conductor, comprising the following steps: S1 obtains dimethyldichlorosilane raw material and performs dechlorination polymerization to generate polydimethylsilane, and then performs high-temperature and high-pressure pyrolysis and rearrangement on the polydimethylsilane to obtain polycarbosilane; Specific methods: S11 uses dimethyldichlorosilane as a raw material and carries out a dechlorination polymerization reaction under an inert atmosphere to generate polydimethylsilane; S12 The polydimethylsilane is placed in a high-pressure reactor and subjected to high-temperature and high-pressure pyrolysis and rearrangement at 350℃~450℃ and 1.5MPa~3.0MPa for 8h~16h to obtain the rearranged product; S13 cools the rearranged product, then performs vacuum distillation to purify it, yielding polycarbosilane.

[0020] S2 melts the polycarbosilane and extrudes it through a spinneret to obtain continuous polycarbosilane fibrils, and then crosslinks the continuous polycarbosilane fibrils to obtain crosslinked fibers; In this embodiment of the invention, the polycarbosilane is melted at 250°C to 350°C to form a uniform melt, which is then quantitatively delivered to the spinneret assembly by a metering pump, extruded through precision spinneret holes, and cooled and shaped in a clean spinning chamber to form continuous and uniform polycarbosilane fibrils. The continuous polycarbosilane fibrils are then crosslinked in one of the following ways: 1. Incubating at 200°C in air for 1 to 3 hours to achieve oxidative crosslinking; 2. Irradiating with an electron beam or ultraviolet light in an oxygen-free atmosphere to improve the thermal stability of the fiber and prevent high-temperature cracking and melting.

[0021] S3 is subjected to high-temperature pyrolysis of the cross-linked fibers under high-purity inert gas conditions, transforming them into a bundle of inorganic silicon carbide fibers. In this embodiment of the invention, the cross-linked fiber is placed in a high-temperature pyrolysis furnace, and high-purity nitrogen or argon (purity ≥99.99%) is introduced. The temperature is increased to 1200℃~1400℃ at a rate of 5℃ / min~15℃ / min and held for 1h~3h to completely transform the organic polymer structure into an inorganic crystal structure. After cooling in the furnace, a continuous bundle of silicon carbide fiber is obtained.

[0022] The silicon carbide fiber bundle described in S4 is fully impregnated with high-temperature resistant resin liquid, and then enters a heated pultrusion mold to be continuously pultruded into a silicon carbide fiber composite mandrel. In this embodiment of the invention, a high-temperature resistant epoxy resin / polyimide resin / cyanate ester resin adhesive is prepared to ensure uniform viscosity, absence of bubbles, and absence of gelation. The silicon carbide fiber 1 is introduced into a constant temperature impregnation tank at an impregnation temperature of 40℃ to 80℃ to allow the resin to fully penetrate the fiber bundle. The resin content is controlled at 20wt% to 40wt%. The impregnated fiber bundle is then continuously formed in a three-stage temperature-controlled pultrusion mold. The gelation zone is 90℃ to 130℃ to allow the resin to initially gel and solidify. The curing zone is 150℃ to 220℃ to allow the resin to fully solidify, forming a dense whole between the fiber and the resin. The cooling zone is ≤60℃ to allow the mandrel to cool and solidify. The pultrusion speed is controlled at 0.5m / min to 3m / min, and the circular silicon carbide fiber 1 composite core is obtained by traction molding and then wound up for later use.

[0023] S5 twists the inner aluminum wire 3 around the silicon carbide fiber 1 composite core rod, and then twists the outer aluminum wire around the inner aluminum wire 3 to obtain the silicon carbide fiber 1 composite core conductor.

[0024] Please see Figure 3 Secondly, the present invention also provides a silicon carbide fiber 1 composite core conductor, which is prepared by the silicon carbide fiber 1 composite core conductor preparation method as described in the first aspect above, including silicon carbide fiber 1, resin layer 2, inner aluminum wire 3 and outer aluminum wire 4, wherein the resin layer 2 is disposed on the outside of the silicon carbide fiber 1, the inner aluminum wire 3 is stranded on the side of the resin layer 2 away from the silicon carbide fiber 1, and the outer aluminum wire 4 is stranded on the side of the inner aluminum wire 3 away from the resin layer 2.

[0025] In this embodiment, the outer aluminum wire 4 and the inner aluminum wire 3 are semi-hard aluminum wire and soft aluminum wire, respectively, and are trapezoidal in shape. The silicon carbide fiber 1, the resin layer 2, the inner aluminum wire 3, and the outer aluminum wire 4 constitute a silicon carbide fiber 1 composite core conductor. This silicon carbide fiber 1 composite core conductor has outstanding advantages such as high strength, high modulus, high temperature resistance, oxidation resistance, corrosion resistance, low thermal expansion coefficient, and large transmission capacity, and has significant economic benefits in power transmission line capacity expansion and renovation projects.

[0026] The above-disclosed embodiments are merely preferred embodiments of a silicon carbide fiber composite core conductor and its preparation method, and should not be construed as limiting the scope of the present application. Those skilled in the art can understand that implementing all or part of the above embodiments and making equivalent changes in accordance with the claims of the present application still fall within the scope of the present application.

Claims

1. A method for preparing a silicon carbide fiber composite core conductor, characterized in that, Includes the following steps: Dimethyldichlorosilane raw material is obtained and subjected to dechlorination polymerization to generate polydimethylsilane. The polydimethylsilane is then subjected to high-temperature and high-pressure pyrolysis and rearrangement to obtain polycarbosilane. The polycarbosilane is melted and extruded through a spinneret to obtain continuous polycarbosilane fibrils, and the continuous polycarbosilane fibrils are crosslinked to obtain crosslinked fibers; Under high-purity inert gas conditions, the cross-linked fibers are subjected to high-temperature pyrolysis to transform them into inorganic silicon carbide fiber bundles. The silicon carbide fiber bundles are fully impregnated with high-temperature resistant resin liquid, and then enter a heated pultrusion mold to be continuously pultruded into silicon carbide fiber composite mandrels. The inner aluminum wire is stranded around the silicon carbide fiber composite core rod, and then the outer aluminum wire is stranded around the inner aluminum wire to obtain a silicon carbide fiber composite core conductor.

2. The method for preparing silicon carbide fiber composite core conductors as described in claim 1, characterized in that, The specific method for obtaining dimethyldichlorosilane raw material through dechlorination polymerization to generate polydimethylsilane, and then subjecting the polydimethylsilane to high-temperature and high-pressure pyrolysis and rearrangement to obtain polycarbosilane is as follows: Dimethyldichlorosilane was used as a raw material and subjected to a dechlorination polymerization reaction under an inert atmosphere to produce polydimethylsilane. The polydimethylsilane was placed in a high-pressure reactor and subjected to high-temperature and high-pressure pyrolysis and rearrangement at 350℃~450℃ and 1.5MPa~3.0MPa for 8h~16h to obtain the rearranged product. The rearranged product was cooled, purified by vacuum distillation, and polycarbosilane was obtained.

3. The method for preparing silicon carbide fiber composite core conductors as described in claim 1, characterized in that, The continuous polycarbosilane fibrils are crosslinked by oxidative crosslinking or by electron beam / ultraviolet irradiation crosslinking in an oxygen-free atmosphere. The chemical crosslinking is carried out by holding the fibers at 200°C in an air atmosphere for 1 to 3 hours.

4. The method for preparing silicon carbide fiber composite core conductors as described in claim 1, characterized in that, The cross-linked fibers require the introduction of high-purity inert gas for high-temperature pyrolysis, and the temperature is increased to 1200℃~1400℃ at a rate of 5℃ / min~15℃ / min, and held for 1h~3h.

5. The method for preparing silicon carbide fiber composite core conductors as described in claim 1, characterized in that, The temperature of the impregnating high-temperature resistant resin solution is 40℃~80℃, and the resin content is 20wt%~40wt%.

6. The method for preparing silicon carbide fiber composite core conductors as described in claim 1, characterized in that, The pultrusion speed is 0.5 m / min to 3 m / min.

7. A silicon carbide fiber composite core conductor, prepared by the method for preparing silicon carbide fiber composite core conductors as described in any one of claims 1-6, characterized in that, It includes silicon carbide fiber, resin layer, inner aluminum wire and outer aluminum wire. The resin layer is disposed outside the silicon carbide fiber. The inner aluminum wire is stranded on the side of the resin layer away from the silicon carbide fiber. The outer aluminum wire is stranded on the side of the inner aluminum wire away from the resin layer.

Images