A kind of oxide continuous fiber with attached nano hair and preparation method thereof

Abstract

This invention relates to the field of oxide fiber technology, and more particularly to a continuous oxide fiber with attached nanofibers and its preparation method, comprising continuous oxide fibers and nanofibers on their surface; the continuous oxide fibers are alumina continuous fibers, silica continuous fibers, alumina-silica continuous fibers, mullite continuous fibers, or alumina-mullite continuous fibers, with a diameter of 0.25-25 μm; the nanofibers are alumina nanofibers, silica nanofibers, alumina-silica nanofibers, mullite nanofibers, or alumina-mullite nanofibers, with a length of 50-500 nm and a diameter of 20-80 nm. The preparation method includes: preparation of a spinning sol; and preparation of the continuous fiber with attached nanofibers. This invention introduces a nanofiber preparation process during the preparation of alumina fibers, achieving integrated forming of a nanofiber coating on the alumina surface without altering the properties of the alumina fibers.

Description

Technical Field

[0001] This invention relates to the field of oxide fiber technology, and in particular to a continuous oxide fiber with attached nanofibers and its preparation method. Background Technology

[0002] In recent years, ceramic fiber materials have received increasing attention. Al2O3 fibers, due to their high surface activity, high mechanical strength, high elastic modulus, low thermal conductivity, good insulation, and strong resistance to chemical corrosion, are widely used in various fields such as weaponry, aviation, aerospace, and automobiles, and advanced countries around the world are continuously expanding their production. Al2O3 ceramic fibers, with their high melting point (maintaining their intact fiber form even at 1650℃ in the atmosphere) and extremely low thermal conductivity, have unique advantages in high-temperature insulation against ablation. Due to their excellent thermal radiation capacity and infrared heating effect, Al2O3 ceramic fibers are excellent infrared radiation materials. Due to their insulation, sound absorption, oxidation resistance, oil resistance, and water resistance, polycrystalline Al2O3 fibers can be used as catalyst carriers. Furthermore, Al2O3 ceramic fibers are soft and elastic, making them ideal sealing materials. Therefore, the selection of alumina materials is of great significance to various industries.

[0003] Chinese patent application CN202111329746.3 discloses a method for preparing continuous alumina fibers using a sol-gel method. Specifically, a sol is propelled by high-pressure air (5-7 MPa) and passes through spinning channels to form alumina fiber precursors, which are then calcined at 1100-1400℃, followed by stretching, winding, and coiling to form continuous alumina fiber long fibers. This invention uses the sol-gel method to prepare alumina fiber long fibers, suitable for fabrics, felts, and fiber-reinforced composites, but it still suffers from insufficient inter-fiber friction.

[0004] Chinese patent application CN202210735011.9 discloses a method for preparing dense, continuous α-alumina fiber materials, including sol preparation, dry spinning, and high-temperature calcination, thereby obtaining continuous α-alumina filaments with alumina as the main crystal form. This invention utilizes mullite sol and zirconium sol for nucleation at relatively low temperatures, promoting fiber formation and inhibiting α-alumina grain growth during sintering. This invention also employs sol-gel spinning to prepare long α-alumina fibers with controllable crystal form, but still suffers from drawbacks such as complex preparation processes.

[0005] Therefore, in order to further enhance the activity of alumina fibers when combined with other materials, the alumina fiber preparation process is physically modified. This application proposes a continuous oxide fiber with attached nanofibers and its preparation method. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a continuous oxide fiber with attached nanofibers and its preparation method. By introducing a nanofiber preparation process during the preparation of alumina fibers, an integrated nanofiber coating is formed on the alumina surface without changing the properties of the alumina fibers.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An oxide continuous fiber with attached nanofibers, consisting of an oxide continuous fiber and nanofibers on its surface;

[0009] The oxide continuous fiber is an alumina continuous fiber, a silica continuous fiber, an alumina-silica continuous fiber, a mullite continuous fiber, or an alumina-mullite continuous fiber, and the diameter of the oxide continuous fiber is 0.25-25 μm.

[0010] The nanofibers are alumina nanofibers, silica nanofibers, alumina-silica nanofibers, mullite nanofibers, or alumina-mullite nanofibers, and the length of the nanofibers is 50-500 nm, and the diameter of the nanofibers is 20-80 nm.

[0011] The linear density of the oxide continuous fiber with attached nanofibers is 100-300 tex, the tensile strength is 1-5 GPa, the tensile modulus is 100-400 GPa, and the high-temperature strength retention rate is 70%-99%.

[0012] This invention also provides a method for preparing continuous oxide fibers with attached nanofibers, comprising the following steps:

[0013] (I) Preparation of spinning sol

[0014] (1) Dissolve aluminum oxide in deionized water to form a solution with a concentration of 0.1-1 g / ml;

[0015] (2) Add aluminum isopropoxide and anhydrous ethanol slowly in small amounts to the solution in step (1) above, and stir magnetically for 5-20 minutes to obtain a white suspension.

[0016] (3) After adding tartaric acid and hydrochloric acid to the white suspension in step (2) in sequence, stir magnetically for 5-12 hours at room temperature to obtain a clear and transparent solution;

[0017] (4) Add polyvinylpyrrolidone to the clear and transparent solution obtained in step (3) and stir vigorously to form a homogeneous and transparent spinnable sol.

[0018] (II) Preparation of continuous fibers with attached nanofibers

[0019] (1) Add the spinnable sol prepared in step (1) into the spinning funnel and pressurize it to make the sol flow out through the spool to form continuous gel fiber.

[0020] (2) Dry the continuous gel fiber formed in step (1) using a hot air drying tunnel, with a hot air temperature of 40 to 120°C and a wind speed of 0.1 to 2 m / s;

[0021] (3) Add the spinnable sol prepared in step (1) into the air spray device and spray it onto the surface of the continuous gel fiber dried in step (2) to form nanofibers and obtain continuous gel fiber with nanofibers attached to the surface.

[0022] (4) The continuous gel fibers with nanofibers attached to the surface in step (3) are subjected to secondary hot air drying at a temperature of 40-120℃ and a wind speed of 0.1-0.5m / s.

[0023] (5) The continuous gel fiber with attached nanofibers in step (4) is dried and aged at 50-150°C for 1-7 days to form raw filaments to be burned.

[0024] (6) The raw silk to be sintered in step (5) is continuously sintered in a tunnel furnace at a stepped temperature of 100 to 1500°C to finally obtain oxide continuous fibers with attached nanofibers.

[0025] Preferably, in step (2) of step (I), the amount of anhydrous ethanol used is 1-20 ml / L, and the amount of aluminum isopropoxide used is 1-10 g / L.

[0026] Preferably, in step (3) of step (I), the amount of hydrochloric acid used in the transparent solution is 1-20 ml / L, and the amount of tartaric acid used is 0.1-10 g / L.

[0027] Preferably, in step (4) of step (I), the amount of polyvinylpyrrolidone added is 0.1-10 g / L.

[0028] Preferably, in step (1) of step (ii), the cross-sectional shape of the continuous gel fiber is circular or elliptical.

[0029] Preferably, in step (3) of step (ii), the needle diameter of the air jet device is 0.6-1.0 mm and the needle extension length is 5-10 mm.

[0030] Preferably, in step (3) of step (ii), the injection rate of the gas injection device is 0.1-10 mL / h and the gas pressure is 0.1-0.5 MPa.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. In the process of preparing alumina fibers, the present invention introduces a nanofiber preparation process, which achieves integrated forming of nanofiber coating on the alumina surface without changing the properties of the alumina fibers.

[0033] 2. This invention forms nanofibers with a length of 50-500 nm on the surface of alumina fibers, which effectively improves the friction between fibers, provides nucleation centers for fiber surface coating, and is beneficial to improving the bonding strength between fibers and interfaces during the preparation of composite materials. Attached Figure Description

[0034] Figure 1 This is a SEM image of the oxide continuous fiber with attached nanofibers prepared in Example 1 of the present invention;

[0035] Figure 2 This is a SEM image of the attached nanofibers prepared in Example 1 of the present invention. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the scope of protection of the present invention. The embodiments described in this invention are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] Example 1:

[0038] An oxide continuous fiber with attached nanofibers, consisting of an oxide continuous fiber and nanofibers on its surface;

[0039] The oxide continuous fiber is an alumina continuous fiber, and the diameter of the oxide continuous fiber is 15 μm;

[0040] The nanofibers are alumina nanofibers, with a length of 100 nm and a diameter of 20 nm.

[0041] The attached nanofiber oxide continuous fiber has a linear density of 160 tex, a tensile strength of 2 GPa, a tensile modulus of 200 GPa, and a high-temperature strength retention rate of 79%.

[0042] A method for preparing a continuous oxide fiber with attached nanofibers includes the following steps:

[0043] (I) Preparation of spinning sol

[0044] (1) Dissolve aluminum oxide in deionized water to form a solution with a concentration of 0.5 g / ml;

[0045] (2) Add aluminum isopropoxide and anhydrous ethanol slowly in small amounts to the solution in step (1) above, and stir magnetically for 20 minutes to obtain a white suspension.

[0046] (3) After adding tartaric acid and hydrochloric acid to the white suspension in step (2) in sequence, the mixture is continuously stirred magnetically at room temperature for 10 hours to obtain a clear and transparent solution.

[0047] (4) Add polyvinylpyrrolidone to the clear and transparent solution obtained in step (3) and stir vigorously to form a homogeneous and transparent spinnable sol.

[0048] (II) Preparation of continuous fibers with attached nanofibers

[0049] (1) Add the spinnable sol prepared in step (1) into the spinning funnel and pressurize it to make the sol flow out through the spool to form continuous gel fiber.

[0050] (2) Dry the continuous gel fiber formed in step (1) using a hot air drying tunnel with a hot air temperature of 70°C and a wind speed of 2m / s;

[0051] (3) Add the spinnable sol prepared in step (1) into the air spray device and spray it onto the surface of the continuous gel fiber dried in step (2) to form nanofibers and obtain continuous gel fiber with nanofibers attached to the surface.

[0052] (4) The continuous gel fiber with nanofibers attached to its surface in step (3) is subjected to a second hot air drying at a temperature of 90°C and a wind speed of 0.5 m / s.

[0053] (5) The continuous gel fiber with attached nanofibers in step (4) is dried and aged at 100°C for 3 days to form raw filaments to be burned.

[0054] (6) The raw silk to be sintered in step (5) is continuously sintered in a tunnel furnace at a stepped temperature of 100 to 1500°C to finally obtain oxide continuous fibers with attached nanofibers.

[0055] In step (2) of step (1), the amount of anhydrous ethanol used is 10 ml / L and the amount of aluminum isopropoxide used is 10 g / L.

[0056] In step (3) of step (1), the amount of hydrochloric acid used in the transparent solution is 10 ml / L, and the amount of tartaric acid used is 0.5 g / L.

[0057] In step (4) of step (1), the amount of polyvinylpyrrolidone added is 2 g / L.

[0058] In step (1) of step (ii), the cross-sectional shape of the continuous gel fiber is circular or elliptical.

[0059] In step (3) of step (ii), the needle diameter of the air jet device is 0.6 mm and the needle extension length is 5 mm.

[0060] In step (3) of step (ii), the injection rate of the gas injection device is 5 mL / h and the gas pressure is 0.5 MPa.

[0061] The oxide continuous fiber with attached alumina nanofibers obtained in this embodiment has a linear density of 160 tex, a tensile strength of 2 GPa, a tensile modulus of 200 GPa, and a high-temperature strength retention rate of 79%. Its performance is comparable to that of oxide continuous fiber without attached nanofibers (a certain brand of AF18 alumina fiber, with a strength ≥1.6 GPa, tensile modulus ≥240 GPa, and linear density of 167 Tex).

[0062] Example 2:

[0063] An oxide continuous fiber with attached nanofibers, consisting of an oxide continuous fiber and nanofibers on its surface;

[0064] The oxide continuous fiber is an alumina continuous fiber, a silica continuous fiber, an alumina-silica continuous fiber, a mullite continuous fiber, or an alumina-mullite continuous fiber, and the diameter of the oxide continuous fiber is 5 μm.

[0065] The nanofibers are alumina nanofibers, silica nanofibers, alumina-silica nanofibers, mullite nanofibers, or alumina-mullite nanofibers, and the length of the nanofibers is 500 nm and the diameter of the nanofibers is 20 nm.

[0066] The attached nanofiber oxide continuous fiber has a linear density of 180 tex, a tensile strength of 2.5 GPa, a tensile modulus of 300 GPa, and a high-temperature strength retention rate of 85%.

[0067] A method for preparing a continuous oxide fiber with attached nanofibers includes the following steps:

[0068] (I) Preparation of spinning sol

[0069] (1) Dissolve aluminum oxide in deionized water to form a solution with a concentration of 0.5 g / ml;

[0070] (2) Add aluminum isopropoxide and anhydrous ethanol slowly in small amounts to the solution in step (1) above, and stir magnetically for 20 minutes to obtain a white suspension.

[0071] (3) After adding tartaric acid and hydrochloric acid to the white suspension in step (2) in sequence, the mixture is continuously stirred magnetically at room temperature for 12 hours to obtain a clear and transparent solution.

[0072] (4) Add polyvinylpyrrolidone to the clear and transparent solution obtained in step (3) and stir vigorously to form a homogeneous and transparent spinnable sol.

[0073] (II) Preparation of continuous fibers with attached nanofibers

[0074] (1) Add the spinnable sol prepared in step (1) into the spinning funnel and pressurize it to make the sol flow out through the spool to form continuous gel fiber.

[0075] (2) The continuous gel fibers formed in step (1) are dried using a hot air drying tunnel at a temperature of 60°C and a wind speed of 1 m / s.

[0076] (3) Add the spinnable sol prepared in step (1) into the air spray device and spray it onto the surface of the continuous gel fiber dried in step (2) to form nanofibers and obtain continuous gel fiber with nanofibers attached to the surface.

[0077] (4) The continuous gel fiber with nanofibers attached to its surface in step (3) is subjected to a second hot air drying at a temperature of 120°C and a wind speed of 0.5 m / s.

[0078] (5) The continuous gel fiber with attached nanofibers in step (4) is dried and aged at 120°C for 7 days to form raw filaments to be burned.

[0079] (6) The raw silk to be sintered in step (5) is continuously sintered in a tunnel furnace at a stepped temperature of 100 to 1500°C to finally obtain oxide continuous fibers with attached nanofibers.

[0080] In step (2) of step (1), the amount of anhydrous ethanol used is 15 ml / L and the amount of aluminum isopropoxide used is 8 g / L.

[0081] In step (3) of step (1), the amount of hydrochloric acid used in the transparent solution is 10 ml / L and the amount of tartaric acid used is 4 g / L.

[0082] In step (4) of step (1), the amount of polyvinylpyrrolidone added is 5 g / L.

[0083] In step (1) of step (ii), the cross-sectional shape of the continuous gel fiber is circular or elliptical.

[0084] In step (3) of step (ii), the needle diameter of the air jet device is 0.6 mm and the needle extension length is 5 mm.

[0085] In step (3) of step (ii), the injection rate of the gas injection device is 4 mL / h and the gas pressure is 0.5 MPa.

[0086] In this embodiment, the obtained oxide continuous fiber with attached alumina nanofibers has a linear density of 180 tex, a tensile strength of 2.5 GPa, a tensile modulus of 300 GPa, and a high-temperature strength retention rate of 85%, which is comparable to the performance of oxide continuous fiber without attached nanofibers (a certain brand of AF18 alumina fiber, with a strength ≥1.6 GPa, a tensile modulus ≥240 GPa, and a linear density of 167 Tex).

[0087] The descriptions and practices disclosed in this invention are readily apparent and understandable to those skilled in the art, and various modifications and refinements can be made without departing from the principles of this invention. Therefore, any modifications or improvements made without departing from the spirit of this invention should also be considered within the scope of protection of this invention.

Claims

1. A method for preparing continuous oxide fibers with attached nanofibers, characterized in that, It consists of continuous oxide fibers and nanofibers on its surface; The oxide continuous fiber is an alumina continuous fiber, and the diameter of the oxide continuous fiber is 0.25-25 μm; The nanofibers are alumina nanofibers, with a length of 50-500 nm and a diameter of 20-80 nm. The linear density of the oxide continuous fiber with attached nanofibers is 100~300 tex, the tensile strength is 1-5 GPa, the tensile modulus is 100-400 GPa, and the high-temperature strength retention rate is 70%-99%. Includes the following steps: (I) Preparation of spinning sol (1) Dissolve aluminum oxide in deionized water to form a solution with a concentration of 0.1-1 g / ml; (2) Add aluminum isopropoxide and anhydrous ethanol slowly in small amounts to the solution in step (1) above, and stir magnetically for 5-20 minutes to obtain a white suspension; (3) After adding tartaric acid and hydrochloric acid to the white suspension in step (2) in sequence, stir magnetically for 5-12 hours at room temperature to obtain a clear and transparent solution; (4) Add polyvinylpyrrolidone to the clear and transparent solution obtained in step (3) and stir vigorously to form a homogeneous and transparent spinnable sol. (II) Preparation of continuous fibers with attached nanofibers (1) Add the spinnable sol prepared in step (1) into the spinning funnel and pressurize it to make the sol flow out through the spool to form continuous gel fiber; (2) The continuous gel fibers formed in step (1) are dried using a hot air drying tunnel at a temperature of 40~120℃ and a wind speed of 0.1~2m / s. (3) Add the spinnable sol prepared in step (1) into the air spray device and spray it onto the surface of the continuous gel fiber dried in step (2) to form nanofibers and obtain continuous gel fiber with nanofibers attached to the surface. (4) The continuous gel fibers with nanofibers attached to the surface in step (3) are subjected to secondary hot air drying at a temperature of 40~120℃ and a wind speed of 0.1~0.5m / s. (5) The continuous gel fiber with attached nanofibers in step (4) is dried and aged at 50~150℃ for 1~7 days to form raw filament to be burned; (6) The raw filaments to be sintered in step (5) are continuously sintered in a tunnel furnace at a stepped temperature of 100~1500℃ to finally obtain continuous oxide fibers with attached nanofibers. In step (2) of step (1), the amount of anhydrous ethanol used is 1-20 ml / L, and the amount of aluminum isopropoxide used is 1-10 g / L; In step (3) of step (1), the amount of hydrochloric acid used in the transparent solution is 1-20 ml / L, and the amount of tartaric acid used is 0.1-10 g / L; In step (4) of step (I), the amount of polyvinylpyrrolidone added is 0.1-10 g / L; In step (1) of step (ii), the cross-sectional shape of the continuous gel fiber is circular or elliptical; In step (3) of step (ii), the needle diameter of the air jet device is 0.6-1.0 mm, and the needle extension length is 5-10 mm; In step (3) of step (ii), the injection rate of the gas injection device is 0.1-10 mL / h and the gas pressure is 0.1-0.5 MPa.

Images