A high-temperature-resistant porous elastic sealing rope and a preparation method and application thereof

Abstract

The application discloses a high-temperature-resistant porous elastic sealing rope and a preparation method and application thereof. A polymer solution is used to anchor and treat fiber bundles, and an interlocking connection structure is constructed on the surface of the fiber, so that the fiber bundles are beneficially bundled and smoothed, and the structural stability in the subsequent twisting process is improved. In a foaming agent system, the twisting and foaming processes are cooperated, wherein the spiral configuration formed by the twisting provides a preset three-dimensional mass transfer and expansion channel for the foaming process, and the interlocking interface between the fibers further separates the channel into a plurality of limited microspaces. After the foaming agent is decomposed by heat, the gas released by the foaming agent preferentially nucleates and grows in the limited microspaces, so that a relatively uniform and dense pore structure is formed; meanwhile, the gas released by the foaming agent in the heat treatment process can further open the graphene sheet layer, and a multi-stage pore structure is constructed in the fiber.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature sealing, specifically relating to a high-temperature resistant porous elastic sealing rope, its preparation method, and its application. Background Technology

[0002] As high-end equipment such as aero-engines, gas turbines, high-temperature industrial furnaces, and aerospace thermal protection systems continue to develop towards higher thrust-to-weight ratios, higher thermal efficiency, and more complex service conditions, the working environment of sealing components is becoming increasingly harsh. Especially under dynamic sealing conditions, sealing materials not only need to withstand extreme thermal environments such as high temperatures and thermal shock for extended periods, but also need to adapt to dynamic effects such as vibration, cyclic loads, and localized friction. Therefore, higher requirements are placed on the high-temperature resistance, elasticity retention, structural stability, and service life of sealing materials.

[0003] Among existing high-temperature sealing materials, inorganic materials have attracted widespread attention due to their excellent high-temperature resistance. Compared with dense materials, elastic sealing materials with a certain porosity are more conducive to achieving functions such as sealing fit, deformation buffering, and gap compensation under high-temperature conditions, thus showing good application prospects in the field of high-temperature dynamic sealing. However, the porous structure reduces the effective load-bearing skeleton of the material, easily leading to local stress concentration; at the same time, inorganic materials generally suffer from problems such as high brittleness and defect sensitivity. Therefore, high-porosity inorganic porous materials usually have problems with low strength and insufficient flexibility, making it difficult to meet the comprehensive requirements of spiral wound high-temperature dynamic seals for deformability, resilience, structural integrity, and long-term service stability.

[0004] To address the insufficient strength and toughness of inorganic porous fiber materials, several improvement schemes have been proposed in existing technologies. For example, some studies have improved the mechanical stability of materials by constructing heterogeneous composite phases to enhance the fiber bulk strength and using the composite phase interface to inhibit crack propagation (Nature Communications, 2023, 14(1): 2643); others have improved the intrinsic brittleness of ceramic fiber materials by constructing semi-crystalline or low-crystallinity ceramic fibers and utilizing the nanocrystalline / amorphous synergistic structure to enhance local strain tolerance, inhibit crack initiation and rapid propagation (Nature, 2022, 606(7916):909-916). The above technical routes have certain effects on improving the strength, flexibility, and crack resistance of inorganic porous fiber materials. However, the above existing technologies still have the following shortcomings: (1) Existing solutions mostly rely on fiber bulk composition design, crystallization state control, phase structure optimization or complex three-dimensional configuration construction, the preparation process is relatively complex, and the requirements for precursor system, process conditions and equipment are high. (2) The above methods are usually costly, and large-scale preparation and continuous processing are difficult, which is not conducive to engineering promotion and application; (3) Existing materials are mostly in the form of aerogel blocks, sheets, films or integral porous structures, which have limited applicability in rope-like seals, irregular gap filling and dynamic service environments; (4) Although some existing materials have good compression recovery or bending properties, there is relatively little research on one-dimensional rope-like high-temperature sealing materials that can be woven, wound, and assembled, making it difficult to directly meet the comprehensive requirements of high temperature resistance, elastic recovery ability, certain mechanical strength and ease of use in the field of high-temperature dynamic sealing.

[0005] Therefore, existing technologies still lack an inorganic porous fiber sealing material that has a relatively simple preparation process, is suitable for continuous processing, and simultaneously possesses high temperature resistance, elastic recovery performance, certain mechanical strength, and wrappability.

[0006] Therefore, it is necessary to provide an inorganic porous fiber sealing rope and its preparation method to improve the material's flexibility, structural stability, compression resilience and practical assembly adaptability while ensuring high temperature resistance, thereby meeting the application requirements in the field of high temperature dynamic sealing. Summary of the Invention

[0007] To address the shortcomings of existing sealing materials, especially fiber-based sealing materials, in terms of flexibility, structural stability, compression resilience, and practical assembly adaptability, this invention provides a high-temperature resistant porous elastic sealing rope, its preparation method, and its applications. This invention first constructs a surface interlocking structure for graphene oxide fibers, then simultaneously performs fiber twisting and foaming. The surface interlocking structure reduces the degrees of freedom between fibers during the twisting-foaming process, preventing fiber separation and concentrating the forces during twisting-foaming within the fibers. This reduces the dissipation of twisting forces and promotes foaming uniformity. More importantly, the helical structure formed by twisting provides predefined "three-dimensional channels" for foaming, while the interlocking interface further divides these channels into confined microspaces. Gases generated by the decomposition of the foaming agent preferentially nucleate within these microspaces, forming a uniformly sized, densely distributed closed-cell structure. This structure avoids macropore defects and skeletal weakening caused by disordered foaming, allowing the porous fibers to achieve high porosity and excellent resilience while maintaining a continuous and complete load-bearing network. Furthermore, the bundle reinforcement effect brought about by the spiral twisting and the efficient stress transfer capability brought about by the interlocking interface ultimately result in porous fibers exhibiting high overall strength, specific strength, and compressive stability. The tensile strength of the twisted fiber rope reaches 0.78 MPa, the elongation at break is 25%, and it exhibits good elastic deformation behavior under strain conditions of 20%, 40%, 60%, 80%, and 90%, demonstrating good compressive resilience.

[0008] One of the technical solutions of this invention is to provide a method for preparing a high-temperature resistant porous elastic sealing rope, comprising the following steps: (1) Graphene oxide fiber bundles are immersed in a polymer solution. By drawing the graphene oxide fiber bundles into the polymer solution for impregnation, the polymer is distributed on the surface of the fiber bundles and at the inter-fiber interfaces, thereby forming an inter-fiber anchoring structure, resulting in graphene oxide fiber bundle 1. The graphene oxide fiber bundle consists of multiple graphene oxide monofilaments with a diameter of 1–30 μm and a number of 200–2000 monofilaments in the fiber bundle. The impregnation process can be carried out in a stainless steel container. Anchoring the fiber bundles with an oligomer solution creates an interlocking connection structure on the fiber surface, which is beneficial for the bundle aggregation and straightening of the fibers and improves the structural stability during subsequent twisting.

[0009] (2) Graphene oxide fiber bundle 1 is immersed in a foaming agent and twisted and foamed to obtain graphene oxide fiber bundle 2; the twist of graphene oxide fiber bundle 2 is 100-500 twists / m, preferably 200-300 twists / m; the twisting method can be selected from one or more of single yarn twisting, ply twisting and compound twisting. Twisting is carried out in the foaming agent system. The helical configuration formed by twisting provides a preset three-dimensional mass transfer and expansion channel for the foaming process. The interlocking interface between fibers further divides the channel into multiple confined microspaces. The gas released after the foaming agent is decomposed by heat preferentially nucleates and grows in the confined microspaces, thereby forming a relatively uniform and dense pore structure. At the same time, the gas released by the foaming agent during the heat treatment process can promote the further opening of the graphene sheets and construct a multi-level pore structure inside the fiber.

[0010] (3) The graphene oxide fiber bundles are subjected to high-temperature heat treatment at 1400-2000℃ under an inert atmosphere, a reducing atmosphere, or a vacuum. During this process, the high temperature transforms the low molecular weight polymer into a hard carbon structure and transforms the graphene oxide into a graphene structure.

[0011] Furthermore, the molecular weight of the polymer is no greater than 100,000.

[0012] Furthermore, the polymer is preferably an organic oligomer or low molecular weight resin that is soluble in organic solvents and can form interfacial bonds on the fiber surface, preferably one or more of polyvinyl butyral, thermoplastic polyurethane, polymethyl methacrylate, polyvinylpyrrolidone, phenolic oligomers, polyimide precursors, and epoxy oligomers.

[0013] Furthermore, the solution concentration of the polymer is 0.1 wt% to 30 wt%.

[0014] Furthermore, in step (1), the traction rate is 10–50 cm / min; the number of immersions is 1–5.

[0015] Furthermore, the mass ratio of the graphene oxide fiber bundle to the polymer solution is 1:(10000~30000).

[0016] Furthermore, the foaming agent is a chemical foaming agent that can decompose and release gas when heated, preferably at least one of sodium bicarbonate, ammonium bicarbonate, ammonium oxalate, and urea.

[0017] Furthermore, in step (2), the foaming treatment temperature is 50–250 °C and the time is 1 min–120 min.

[0018] The second technical solution of the present invention is to provide a high-temperature resistant porous elastic sealing rope prepared by the above method. The sealing rope has a twisted rope structure, a porous internal structure, and a cross-sectional area of ​​1 to 5 mm².

[0019] The third technical solution of the present invention is to provide the application of the above-mentioned high-temperature resistant porous elastic sealing rope.

[0020] The advantages of this invention are: the porosity of the prepared high-temperature resistant porous elastic sealing rope reaches 80%; the tensile strength reaches 0.78 MPa; it has heat-resistant structural stability after heat treatment at 1400-2000℃; the elasticity reaches 90%; and it is suitable for the comprehensive requirements of high-temperature resistance, elastic recovery ability, and certain mechanical strength in the field of high-temperature dynamic sealing. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of graphene oxide fiber bundles to twisted porous graphene fiber ropes in the embodiments of this application.

[0022] Figure 2 , 3 This is a physical image of the high-temperature resistant porous elastic sealing rope in Embodiment 1 of this application.

[0023] Figure 4 This is an electron microscope image of the twisted porous fiber bundle in Example 1 of this application. The scale bar is 10 μm.

[0024] Figure 5 This is the tensile stress-strain curve in Embodiment 1 of this application.

[0025] Figure 6 This is the compressive stress-strain curve in Embodiment 1 of this application.

[0026] Figure 7 This is the compressive stress-strain curve of the graphite packing in Embodiment 1 of this application.

[0027] Figure 8 These are photographs of the graphite packing before and after compression in Embodiment 1 of this application.

[0028] Figure 9 The image shows an electron microscope image of an unanchored and untwisted porous fiber bundle in Comparative Example 1 of this application. The scale bar is 10 μm.

[0029] Figure 10 The tensile stress-strain curve of the unanchored and untwisted porous fiber bundle in Comparative Example 1 of this application is shown.

[0030] Figure 11 This is an electron microscope image of a porous fiber bundle that is anchored but not twisted in Comparative Example 2 of this application. The scale bar is 10 μm.

[0031] Figure 12 The image shown is an electron microscope image of a non-anchored, twisted porous fiber bundle in Comparative Example 3 of this application. The scale bar is 10 μm.

[0032] Figure 13 The tensile stress-strain curve of the porous fiber bundle without anchoring but only twisted in Comparative Example 3 of this application is shown. Detailed Implementation

[0033] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0034] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0035] In this application, the compressive stress-strain curve was tested using a Rigol universal testing machine, and the test was conducted in accordance with the standard GB / T8168-2008 "Static Compression Test Method for Packaging Cushioning Materials".

[0036] In this application, the tensile test was conducted using a Rigel universal testing machine, in accordance with the standard GB / T1040.1-2025 "Determination of Tensile Properties of Plastics".

[0037] The embodiments of the present invention will be further described below with reference to several examples.

[0038] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0039] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0040] Example 1 (1) Take a 10 m long graphene oxide fiber bundle, which consists of 1000 monofilaments, each monofilament having a diameter of 10 μm. Immerse the graphene oxide fiber bundle in a 5% (w / w) polyvinylpyrrolidone (PVP, weight-average molecular weight of 58,000) solution for anchoring treatment, wherein the mass ratio of the fiber bundle to the PVP solution is 1:10 (mg:g), the immersion rate is 10 cm / min, and the immersion is repeated 5 times.

[0041] (2) The anchored filament bundles are immersed in a solution containing a foaming agent, and then twisted and foamed in an ammonium oxalate foaming agent solution. The twisting structures used include single-strand twisting, four-strand twisting and six-strand twisting, with a twist of 200 twists / m, a foaming temperature of 200 ℃ and a foaming time of 60 minutes.

[0042] (3) The obtained twisted porous graphene oxide fiber rope is further subjected to high temperature heat treatment at 1800 ℃ to finally obtain a high temperature resistant porous elastic sealing rope.

[0043] The resulting high-temperature resistant porous elastic sealing rope has the following structural morphology: Figure 2 , Figure 3 and Figure 4 As shown, the diameter of the monofilament porous fibers ranges from 10 to 50 μm, and the pore size ranges from 0.5 to 10 μm, indicating that the foaming treatment can effectively construct a porous structure within the fiber. Tensile test results show that the tensile strength of the twisted fiber rope reaches 0.78 MPa, and the elongation at break is 25%. Its tensile performance test curve is shown in the figure. Figure 5 As shown in the figure. The compression test results further demonstrate that the sealing rope exhibits good elastic deformation behavior under strain conditions of 20%, 40%, 60%, 80%, and 90%, as shown in the compression stress-strain curves. Figure 6 As shown in the figure. The above results demonstrate that the constructed porous twisted structure can impart excellent compressive resilience properties to the material.

[0044] The compressive elastic behavior of the prepared high-temperature resistant porous elastic sealing rope was compared with that of commercial graphite packing. The results are as follows: Figure 7 As shown, the graphite packing exhibits a sudden drop in stress when the strain reaches 20%, indicating that it fails under relatively small compressive deformation. Combined with... Figure 8 It can be seen that the graphite packing has undergone significant fracture damage under this strain condition, which will seriously affect its stability and reliability when used as a dynamic seal.

[0045] In addition, graphite packing exhibits high compressive stress during compression, which usually requires a greater clamping force to achieve an effective seal. This not only increases the difficulty of installation but also places higher demands on the materials being sealed.

[0046] Example 2 (1) Take a 10 m long graphene oxide fiber bundle, which consists of 1000 monofilaments, each with a diameter of 10 μm. Immerse the graphene oxide fiber bundle in a 2% polymethyl methacrylate (PMMA) solution (weight average molecular weight of 15,000) for anchoring treatment, wherein the mass ratio of the fiber bundle to the PMMA solution is 1:20 (mg:g), the immersion rate is 10 cm / min, and the immersion is performed once.

[0047] (2) The anchored filament bundles were immersed in a solution containing a foaming agent and then twisted and foamed in a sodium bicarbonate solution. The twisting structure used was single-strand twisting, with a twist of 100 twists / m, a foaming temperature of 50 ℃, and a foaming time of 120 minutes.

[0048] (3) The obtained twisted porous graphene oxide fiber rope is further subjected to high temperature heat treatment at 1400℃ to finally obtain a high temperature resistant porous elastic sealing rope.

[0049] Example 3 (1) Take a 10 m long graphene oxide fiber bundle, which consists of 1000 monofilaments, each with a diameter of 10 μm. Immerse the graphene oxide fiber bundle in a 10% polyvinyl butyral solution (weight-average molecular weight of 40,000) for anchoring treatment, wherein the mass ratio of the fiber bundle to the polyvinyl butyral solution is 1:30 (mg:g), the immersion rate is 50 cm / min, and the immersion is repeated 3 times.

[0050] (2) The anchored filament bundles were immersed in a solution containing a foaming agent and then twisted and foamed in an ammonium bicarbonate solution. The twisting structure used was four-strand twisting with a twist rate of 500 twists / m, a foaming temperature of 250 ℃, and a foaming time of 1 minute.

[0051] (3) The obtained twisted porous graphene oxide fiber rope is further subjected to high temperature heat treatment at 1600 ℃ to finally obtain a high temperature resistant porous elastic sealing rope.

[0052] Comparative Example 1 A 10 m long bundle of graphene oxide fibers, composed of 1000 monofilaments each with a diameter of 10 μm, was taken. This bundle, without anchoring treatment, was directly immersed in an ammonium oxalate foaming agent solution and foamed at 200 °C. Subsequently, the obtained porous graphene oxide fibers were further heat-treated at 1800 °C to finally obtain a dispersed, high-temperature resistant porous fiber bundle with the following surface morphology. Figure 9 As shown. Compared with the high-temperature resistant porous elastic sealing rope prepared in Example 1, the sample has poor uniformity of pore size distribution of the filament bundle, lower pore density formed by foaming, and a significantly reduced number of pores.

[0053] Mechanical property test results show that the tensile strength of the untwisted fiber bundle is only about 50% of that of the twisted fiber rope, and its tensile stress-strain curve is as follows. Figure 10 As shown.

[0054] Comparative Example 2 A 10 m long graphene oxide fiber bundle, composed of 1000 monofilaments, each with a diameter of 10 μm, was selected. The graphene oxide fiber bundle was immersed in a polyvinylpyrrolidone (PVP) solution for anchoring treatment, wherein the mass ratio of the fiber bundle to the PPVP solution was 1:10 (mg:g), the immersion rate was 10 cm / min, and the immersion was repeated 5 times. Subsequently, the anchored fiber bundle was immersed in a solution containing ammonium oxalate foaming agent and foamed at 200 °C. The resulting porous graphene oxide fibers were further subjected to high-temperature heat treatment at 1800 °C to finally obtain a dispersed, high-temperature resistant porous fiber bundle with the following surface morphology. Figure 11 As shown. Since the foaming of the filament bundle in this comparative example is not carried out under twisting conditions, the spiral configuration formed by twisting cannot provide a preset three-dimensional mass transfer and expansion channel for the foaming process. The gas released after the foaming agent is decomposed by heat has a random dispersion path. Therefore, the pore size distribution of its filament bundle is uneven, and there are a large number of unfoamed areas.

[0055] Comparative Example 3 A 10 m long graphene oxide fiber bundle, composed of 1000 monofilaments, each with a diameter of 10 μm, was taken. The bundle was immersed in an ammonium oxalate foaming agent solution and subjected to twisting and foaming treatments. The twisting degree was 200 twists / m, the foaming temperature was 200 ℃, and the foaming time was 60 min. Subsequently, the obtained porous graphene oxide fibers were further subjected to high-temperature heat treatment at 1800 ℃, ultimately yielding a relatively dispersed, high-temperature resistant porous fiber bundle with the following surface morphology. Figure 12As shown. Because the twisting in this comparative example was not performed under anchoring conditions, an interlocking connection structure could not be formed on the fiber surface, which is detrimental to the bundling and straightening of the fiber bundles. The difficulty in forming an effective interlocking connection structure on the fiber surface further hinders the bundling and straightening of the fiber bundles and weakens the structural stability during subsequent twisting and foaming processes. For example... Figure 13 As shown, compared with the fiber bundles obtained under the combined effect of anchoring and foaming, the tensile strength of the unanchored and twisted samples in this comparative example is about 0.65 MPa. In addition, the fiber bundles obtained under the combined effect maintain a higher load-bearing level in a larger strain range, indicating that the anchoring treatment is beneficial to improving the structural integrity and mechanical stability of the fiber bundles.

[0056] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

Claims

1. A method for preparing a high-temperature resistant porous elastic sealing rope, characterized in that, Includes the following steps: (1) The graphene oxide fiber bundle is immersed in a polymer solution. The graphene oxide fiber bundle is drawn into the polymer solution for impregnation treatment, so that the polymer is distributed on the surface of the fiber bundle and the interface between the fibers to obtain the graphene oxide fiber bundle 1. (2) The graphene oxide fiber bundle 1 is immersed in a foaming agent and twisted and foamed to obtain the graphene oxide fiber bundle 2; the twist of the graphene oxide fiber bundle 2 is 100 to 500 twists / m; (3) The graphene oxide fiber bundles are subjected to high-temperature heat treatment at 1400-2000℃ under inert atmosphere, reducing atmosphere or vacuum conditions.

2. The method according to claim 1, characterized in that, The molecular weight of the polymer is no greater than 100,000.

3. The method according to claim 2, characterized in that, The polymer is one or more of the following: polyvinyl butyral, thermoplastic polyurethane, polymethyl methacrylate, polyvinylpyrrolidone, phenolic oligomers, polyimide precursors, and epoxy oligomers.

4. The method according to claim 1, characterized in that, In step (1), the traction rate is 10-50 cm / min; the number of immersion treatments is 1-5.

5. The method according to claim 1, characterized in that, The polymer solution concentration is 0.1 wt% to 30 wt%.

6. The method according to claim 1, characterized in that, The mass ratio of the graphene oxide fiber bundle to the polymer solution is 1:(10000~30000).

7. The method according to claim 1, characterized in that, The foaming agent is at least one of sodium bicarbonate, ammonium bicarbonate, ammonium oxalate, and urea.

8. The method according to claim 1, characterized in that, In step (2), the foaming process is carried out at a temperature of 50 to 250°C for 1 to 120 minutes.

9. A high-temperature resistant porous elastic sealing rope prepared by the method of claim 1.

10. An application of the high-temperature resistant porous elastic sealing rope as described in claim 9.

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