Alumina nanofiber yarn and method of making the same

Abstract

The application relates to an alumina nanofiber yarn and a preparation method thereof, and the method comprises the following steps: obtaining a precursor spinning solution; performing electrostatic spinning on the precursor spinning solution in a single electrode mode, so that the electric field distribution between a needle head and a fiber collector is uniform, and an alumina nanofiber yarn raw silk is obtained; and performing segmented continuous sintering on the alumina nanofiber yarn raw silk under the action of a constant tension, so that the nanofiber yarn raw silk uniformly shrinks under the drawing action of the constant tension, and an alumina nanofiber yarn is obtained. The application solves the technical problem that the uniformity of the existing alumina nanofiber yarn is poor, and also realizes the advantage that the alumina nanofiber yarn can be continuously prepared.

Description

Technical Field

[0001] This application relates to the field of inorganic non-metallic materials, and in particular to an alumina nanofiber yarn and its preparation method. Background Technology

[0002] Alumina nanofibers not only possess the advantages of micron-sized alumina fibers, but also exhibit tunable pore structure, low thermal conductivity, and high specific surface area. The sol-gel method combined with electrospinning is a simple and effective method for preparing alumina nanofibers. However, alumina nanofibers need to be processed into one-dimensional yarns to be applied in various textile processing technologies.

[0003] Currently, the development of nanofiber yarn materials faces challenges such as complex process flow, poor uniformity of nanofiber yarns, and inability to produce them continuously. When auxiliary electrodes are introduced, the electric fields between the positive and negative electrodes interfere with each other, making it difficult to control the electric field distribution and intensity, thus preventing the continuous, uniform, and stable spinning of nanofiber yarns. Summary of the Invention

[0004] This application provides an alumina nanofiber yarn and its preparation method to solve the technical problem of poor uniformity in existing alumina nanofiber yarns.

[0005] In a first aspect, this application provides a method for preparing alumina nanofiber yarn, the method comprising:

[0006] The precursor spinning solution was obtained;

[0007] Electrospinning of the precursor spinning solution was performed using a single electrode to ensure a uniform electric field distribution between the needle and the yarn collector, thereby obtaining alumina nanofiber yarn precursor.

[0008] The alumina nanofiber yarn precursor is subjected to segmented continuous sintering under constant tension, so that the nanofiber yarn precursor shrinks uniformly under the constant tension stretching action to obtain alumina nanofiber yarn.

[0009] Optionally, the single electrode method can be a single positive electrode method or a single negative electrode method; wherein,

[0010] When the single positive electrode method is used, the electrode process parameters include: spinning electrode voltage of 9kV to 20kV, injection pump flow rate of 0.1ml / h to 1.5ml / h, and rotation speed of the rotating fiber collector of 10r / min to 200r / min;

[0011] When the single negative electrode method is used, the electrode process parameters include: spinning electrode voltage of (-9)kV to (-20)kV, injection pump flow rate of 0.1ml / h to 1.5ml / h, and rotation speed of the spinning collector of 10r / min to 200r / min.

[0012] Optionally, when using the single positive electrode method, the spinning electrode voltage is 11kV to 15kV, the injection pump flow rate is 0.3ml / h to 0.8ml / h, and the rotation speed of the rotating fiber collector is 30r / min to 100r / min.

[0013] Optionally, the tension is 10cN to 200cN.

[0014] Optionally, the tension is 10cN to 100cN.

[0015] Optionally, the step of performing segmented continuous sintering of the alumina nanofiber yarn precursor under constant tension, so that the nanofiber yarn precursor uniformly shrinks under the constant tension to obtain alumina nanofiber yarn, includes:

[0016] The alumina nanofiber yarn precursor is subjected to segmented continuous sintering under constant tension in a winding manner, so that the nanofiber yarn precursor shrinks uniformly under the stretching action of constant tension to obtain alumina nanofiber yarn.

[0017] Optionally, the winding speed is 0.01 m / min to 10 m / min.

[0018] Optionally, the precursor spinning solution includes:

[0019] Aluminum source and oxide source are chemically reacted to obtain precursor spinning sol;

[0020] The precursor spinning sol is aged and then mixed with spinning aids to obtain the precursor spinning solution.

[0021] Secondly, this application provides an alumina nanofiber yarn, which is prepared by the method described in any one of the embodiments of the first aspect.

[0022] Optionally, the properties of the alumina nanofiber yarn include at least one of the following: linear density of 30 tex to 100 tex, yarn diameter of 100 μm to 600 μm, single fiber diameter of 100 nm to 800 nm, and breaking strength of 50 cN to 300 cN.

[0023] The technical solutions provided in this application have the following advantages compared with the prior art:

[0024] The method for preparing alumina nanofiber yarn provided in this application involves electrospinning the precursor spinning solution using a single electrode. This ensures a uniform electric field distribution between the needle and the yarn collector, avoiding the interference between the electric fields caused by simultaneous use of positive and negative electrodes and the resulting unstable spinning jet, thus improving the uniformity of the alumina nanofiber yarn precursor. Furthermore, the alumina nanofiber yarn precursor is subjected to segmented continuous sintering under constant tension. Due to the stretching effect of the constant tension, uniform shrinkage of the nanofiber yarn is ensured, further enhancing its uniformity. In summary, this method solves the technical problem of poor uniformity in existing alumina nanofiber yarns. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic flowchart illustrating a method for preparing alumina nanofiber yarn provided in this application embodiment;

[0028] Figure 2 The infrared spectrum of the aluminosilicate sol in Example 1 of this application;

[0029] Figure 3 The rheological curve of the alumina precursor spinning solution in Example 1 of this application is shown.

[0030] Figure 4 This is an optical image of the continuous alumina nanofiber yarn in Example 1 of this application;

[0031] Figure 5 This is a low-magnification scanning electron microscope image of the alumina nanofiber yarn in Example 1 of this application;

[0032] Figure 6 This is a high-magnification scanning electron microscope image of the alumina nanofiber yarn in Example 1 of this application. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0035] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0037] Firstly, this application provides a method for preparing alumina nanofiber yarn; please refer to [link to relevant documentation]. Figure 1 The method includes:

[0038] S1. Obtain the precursor spinning solution;

[0039] In some embodiments, obtaining the precursor spinning solution includes: chemically reacting an aluminum source and an oxide source to obtain a precursor spinning sol; aging the precursor spinning sol and then mixing it with a spinning aid to obtain the precursor spinning solution.

[0040] In this embodiment, an aluminum source and an oxide source are chemically reacted to obtain a precursor spinning sol. This chemical reaction can be hydrolysis or polycondensation. By hydrolyzing or polycondensing the aluminum source and other oxide sources together, a precursor sol with a uniform structure and stable properties can be obtained. Specifically, step S1 includes: dissolving an aluminum source, a silicon source, or a zirconium source in a molar ratio of 1:(0.01-0.70) (based on the content of Al2O3, SiO2, and ZrO2) in a solvent, slowly adding 0-5% (molar percentage) of other oxide sources at the reaction temperature, continuously stirring to obtain a precursor sol, aging it for a period of time, and adding a spinning aid to obtain a precursor spinning solution. The aluminum source, silicon source, zirconium source, or other oxide source mentioned above are nano-oxides, hydroxides, organic compounds, salts, or colloidal aqueous dispersions of Al, Si, Zr, Fe, Ti, Y, and Mg. More preferably, the aluminum source is at least one of aluminum isopropoxide and basic aluminum acetate, the silicon source is at least one of tetraethyl silicate and silica sol, and the zirconium source is at least one of zirconium acetate and zirconium sol. The spinning aid mentioned above is at least one of PVA, PAN, and PVP, the concentration of the spinning aid is 5-20 wt.%, and the weight ratio of the precursor sol to the spinning aid is 1:(0.01-1). More preferably, the weight ratio is 1:(0.01-0.2).

[0041] S2. Electrospinning the precursor spinning solution using a single electrode method to make the electric field distribution between the needle and the yarn collector uniform, thereby obtaining alumina nanofiber yarn precursor.

[0042] In some embodiments, the single electrode configuration is either a single positive electrode configuration or a single negative electrode configuration; wherein,

[0043] When the single positive electrode method is used, the electrode process parameters include: spinning electrode voltage of 9kV to 20kV, injection pump flow rate of 0.1ml / h to 1.5ml / h, and rotation speed of the rotating fiber collector of 10r / min to 200r / min;

[0044] When the single negative electrode method is used, the electrode process parameters include: spinning electrode voltage of (-9)kV to (-20)kV, injection pump flow rate of 0.1ml / h to 1.5ml / h, and rotation speed of the spinning collector of 10r / min to 200r / min.

[0045] In some embodiments, when the single positive electrode method is used, the spinning electrode voltage is 11kV to 15kV, the injection pump flow rate is 0.3ml / h to 0.8ml / h, and the rotation speed of the rotating fiber collector is 30r / min to 100r / min.

[0046] In this embodiment, a single-electrode method is used to electrospin the precursor spinning solution. The needle is connected to either a positive or negative high voltage, and the rotating conical yarn collector is grounded. By controlling the electrode process parameters, alumina nanofibers form a spindle-shaped nanofiber film on the surface of the conical yarn collector. By pulling the ends of the spindle shape, the yarn passes through a bundling guide wheel and a winding device to obtain continuous alumina nanofiber yarn. The single-electrode method ensures a uniform electric field distribution between the needle and the yarn collector, avoiding the problem of mutual interference when using both positive and negative electrodes simultaneously. This results in better spinning stability and reliability, improved spinning efficiency and controllability, and the realization of continuous spinning of nanofiber yarn. Specifically, when using the single positive electrode method, the spinning electrode voltage can be 9kV, 11kV, 13kV, 15kV, 17kV, 19kV, 20kV, etc., the injection pump flow rate can be 0.1ml / h, 0.3ml / h, 0.5ml / h, 0.7ml / h, 0.9ml / h, 1.1ml / h, 1.3ml / h, 1.5ml / h, etc., and the rotation speed of the rotating fiber collector can be 10r / min, 20r / min, 30r / min, 40r / min, 50r / min, 100r / min, 150r / min, 200r / min, etc. Preferably, the spinning electrode voltage can be 11kV to 15kV, the injection pump flow rate can be 0.3ml / h to 0.8ml / h, and the rotation speed of the rotating fiber collector can be 30r / min to 100r / min. When using the single negative electrode method, the spinning electrode voltage can be -9kV, -11kV, -13kV, -15kV, -17kV, -19kV, -20kV, etc., and the injection pump flow rate and the rotation speed of the spinning collector can be the same as those of the single positive electrode method.

[0047] S3. The alumina nanofiber yarn precursor is subjected to segmented continuous sintering under constant tension so that the nanofiber yarn precursor shrinks uniformly under the stretching action of constant tension to obtain alumina nanofiber yarn.

[0048] In some embodiments, the tension is 10 cN to 200 cN.

[0049] In some embodiments, the tension is 10 cN to 100 cN.

[0050] In some embodiments, the step of performing segmented continuous sintering of the alumina nanofiber yarn precursor under constant tension, so that the nanofiber yarn precursor uniformly shrinks under the constant tension to obtain alumina nanofiber yarn, includes:

[0051] The alumina nanofiber yarn precursor is subjected to segmented continuous sintering under constant tension in a winding manner, so that the nanofiber yarn precursor shrinks uniformly under the stretching action of constant tension to obtain alumina nanofiber yarn.

[0052] In some embodiments, the winding speed is 0.01 m / min to 10 m / min.

[0053] In this embodiment, segmented sintering enables continuous sintering of alumina nanofiber yarns. Compared to staged heating and holding sintering, the segmented continuous sintering process is simpler and easier for industrial production. Sintering the alumina nanofiber yarns under constant tension ensures uniform shrinkage, improves yarn compactness and interfiber friction, and achieves a maximum breaking strength of 300 cN. Specifically, the tension can be 10 cN, 20 cN, 30 cN, 40 cN, 50 cN, 100 cN, 150 cN, 200 cN, etc., preferably between 10 cN and 100 cN. Furthermore, the segmented continuous sintering can consist of three isothermal zones, and more preferably, it consists of five isothermal zones: zone A (100–300℃), zone B (300–600℃), zone C (600–900℃), zone D (900–1200℃), and zone E (1200–1600℃). Segmented sintering is achieved in a segmented high-temperature furnace. The aforementioned constant tension is achieved through a winding method, which is implemented using a fiber winding system. The winding speed can be 0.01 m / min, 0.05 m / min, 0.1 m / min, 0.5 m / min, 1 m / min, 2 m / min, 4 m / min, 6 m / min, 8 m / min, 10 m / min, etc. Preferably, the winding speed can be 0.01 m / min to 5 m / min. Specifically, the alumina nanofiber yarn precursor is continuously sintered in a segmented high-temperature furnace using a fiber winding system to obtain alumina nanofiber yarn, and the fiber winding system is controlled to maintain constant speed and tension.

[0054] In summary, the method for preparing alumina nanofiber yarn provided in this application has a simple process flow, is suitable for industrial production, and produces continuous alumina nanofiber yarn. It possesses the dual advantages of micron- and nano-sized alumina fibers, exhibiting uniformity, density, flexibility, and weavability, making it suitable for weaving into alumina fiber fabrics applicable to fields such as high-temperature super-insulation. This method not only solves the technical problem of poor uniformity in existing alumina nanofiber yarns but also achieves the advantage of continuous alumina nanofiber yarn preparation.

[0055] Secondly, this application provides an alumina nanofiber yarn, which is prepared by the method described in any one of the embodiments of the first aspect.

[0056] In some embodiments, the properties of the alumina nanofiber yarn include at least one of the following: linear density of 30 tex to 100 tex, yarn diameter of 100 μm to 600 μm, single fiber diameter of 100 nm to 800 nm, and breaking strength of 50 cN to 300 cN.

[0057] In the embodiments of this application, the linear density of the alumina nanofiber yarn can reach 30 tex to 100 tex, the yarn diameter can reach 100 μm to 600 μm, the single fiber diameter can reach 100 nm to 800 nm, and the breaking strength can reach 50 cN to 300 cN. Furthermore, the above-mentioned continuous alumina nanofiber yarn, by molar percentage, comprises 60 to 80% Al₂O₃, 20 to 40% SiO₂, and 0 to 2% Fe₂O₃ / TiO₂; or the above-mentioned continuous alumina nanofiber yarn, by molar percentage, comprises 75 to 95% Al₂O₃, 5 to 20% ZrO₂, and 0 to 5% Y₂O₃ / MgO.

[0058] The alumina nanofiber yarn is realized based on the above-described preparation method of alumina nanofiber yarn. The specific steps of the preparation method of alumina nanofiber yarn can be referred to the above embodiments. Since the alumina nanofiber yarn adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0059] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0060] In a first aspect, this application provides a method for preparing alumina nanofiber yarn, the method comprising:

[0061] S11. Obtain the precursor spinning solution;

[0062] S21. Electrospinning the precursor spinning solution using a single electrode method to make the electric field distribution between the needle and the yarn collector uniform, thereby obtaining alumina nanofiber yarn precursor.

[0063] S31. The alumina nanofiber yarn precursor is subjected to segmented continuous sintering under constant tension, so that the nanofiber yarn precursor shrinks uniformly under the constant tension stretching action to obtain alumina nanofiber yarn. For specific process steps, please refer to Examples 1 to 7.

[0064] Example 1

[0065] (1) Preparation of precursor spinning solution

[0066] Dissolve 100g Al(NO3)3·9H2O and 180g aluminum isopropoxide in 500ml deionized water, add an appropriate amount of acetic acid to adjust the pH of the solution to 2.0, slowly add 35g tetraethyl silicate under 60℃ water bath conditions, and stir continuously for 12h to obtain a transparent aluminum silicate sol.

[0067] Weigh 50g of iron sol, the Fe2O3 equivalent content in the sol is 1.0%, stir and mix the aluminum silicate sol and iron sol evenly, age for a period of time, add 10wt.% PVA solution, and mix the aluminum silicate sol and PVA solution at a ratio of 1:0.2 to obtain the precursor spinning solution.

[0068] (2) Preparation of continuous alumina nanofiber yarn precursor

[0069] The precursor spinning solution obtained in step (1) is electrospun using a single positive electrode. The spinning electrode voltage is 13kV, the injection pump flow rate is 0.6ml / h, and the rotation speed of the spinning collector is 50r / min. The spun alumina nanofiber yarn is collected by a bundle guide wheel and a yarn collection device. The collected alumina nanofiber yarn is uniform and continuous.

[0070] (3) Sintering of alumina nanofiber yarns

[0071] The continuous alumina nanofiber yarn precursor prepared in step (2) is fed into a multi-segment high-temperature furnace for sintering through a fiber winding system. The constant temperature zone is divided into five segments: 150℃, 400℃, 850℃, 1100℃ and 1400℃. The working speed of the winding system is 0.05m / min and the tension is 70cN.

[0072] The infrared spectrum of the aluminosilicate sol prepared in Example 1 is shown below. Figure 2As shown in the figure, the aluminum silica sol contains characteristic absorption peaks of Al-OH, Si-O-Si, Al-O-Si, AlO4, and AlO6, and the sol particles aggregate to form a polymer.

[0073] The rheological curve of the alumina precursor spinning solution prepared in Example 1 is shown below. Figure 3 As shown in the figure, the viscosity of the sol remains essentially unchanged with the increase of shear rate, exhibiting characteristics similar to a Newtonian fluid. This indicates that the precursor spinning solution contains linear macromolecules and has good spinnability.

[0074] The continuous alumina nanofiber yarn prepared in Example 1 is as follows: Figures 4-6 As shown in the figure, the obtained continuous alumina nanofiber yarn is composed of nearly parallel alumina nanofibers twisted axially. The surface of each fiber is very smooth, without defects such as pores or cracks. After twisting, the outer fibers of the yarn twist and deform, squeezing the inner fibers, increasing the friction between the fibers and improving the uniformity and mechanical properties of the yarn.

[0075] The obtained alumina nanofiber yarn has a diameter of 450 μm, a linear density of 60 tex, a single fiber diameter of 550 nm to 650 nm, and a breaking strength of 280 cN.

[0076] Example 2

[0077] (1) Preparation of precursor spinning solution

[0078] Same as Example 1.

[0079] (2) Preparation of continuous alumina nanofiber yarn precursor

[0080] The precursor spinning solution obtained in step (1) is electrospun using a single negative electrode method. The spinning electrode voltage is -11kV, the injection pump flow rate is 0.3ml / h, and the rotation speed of the spinning collector is 50r / min. The spun alumina nanofiber yarn is collected by a bundling guide wheel and a yarn collection device. The collected alumina nanofiber yarn is uniform and continuous.

[0081] (3) Sintering of alumina nanofiber yarns

[0082] Same as Example 1.

[0083] The obtained alumina nanofiber yarn has a diameter of 260 μm, a linear density of 35 tex, a single fiber diameter of 650 nm to 800 nm, and a breaking strength of 126 cN.

[0084] Example 3

[0085] (1) Preparation of precursor spinning solution

[0086] Same as Example 1, except that 75g of tetraethyl silicate was added.

[0087] (2) Preparation of continuous alumina nanofiber yarn precursor

[0088] Same as Example 1.

[0089] (3) Sintering of alumina nanofiber yarns

[0090] The continuous alumina nanofiber yarn precursor prepared in step (2) is fed into a multi-segment high-temperature furnace for sintering through a fiber winding system. The constant temperature zone is divided into four segments: 150℃, 400℃, 850℃ and 1350℃. The working speed of the winding system is 0.1m / min and the tension is 50cN.

[0091] The obtained alumina nanofiber yarn has a diameter of 520 μm, a linear density of 72 tex, a single fiber diameter of 600 nm to 750 nm, and a breaking strength of 180 cN.

[0092] Example 4

[0093] (1) Preparation of precursor spinning solution

[0094] 100g Al(NO3)3·9H2O, 140g basic aluminum acetate, and 500ml deionized water were mixed. An appropriate amount of dilute nitric acid was added to adjust the pH of the solution to 2.0. 74g acidic silica sol and 1.5g tetrabutyl titanate were slowly added under 80℃ water bath conditions. The equivalent SiO2 content in the acidic silica sol was 30%. The mixture was stirred continuously for 20 hours to obtain a transparent aluminosilicate sol. After aging for a period of time, a 15wt.% PVP solution was added. The aluminosilicate sol and PVP solution were mixed at a ratio of 1:0.05 to obtain the precursor spinning solution.

[0095] (2) Preparation of continuous alumina nanofiber yarn precursor

[0096] The precursor spinning solution obtained in step (1) is electrospun using a single positive electrode. The spinning electrode voltage is 15kV, the injection pump flow rate is 0.4ml / h, and the rotation speed of the spinning collector is 50r / min. The spun alumina nanofiber yarn is collected by a bundling guide wheel and a yarn collection device. The collected alumina nanofiber yarn is uniform and continuous.

[0097] (3) Sintering of alumina nanofiber yarns

[0098] Same as Example 3

[0099] The obtained alumina nanofiber yarn has a diameter of 220 μm, a linear density of 40 tex, a single fiber diameter of 200 nm to 350 nm, and a breaking strength of 172 cN.

[0100] Example 5

[0101] (1) Preparation of precursor spinning solution

[0102] 150g of Al(NO3)3·9H2O and 260g of aluminum isopropoxide were dissolved in 700ml of deionized water. An appropriate amount of acetic acid was added to adjust the pH of the solution to 2.0. Under a 60℃ water bath, 45g of zirconium acetate and 4.0g of Y(NO3)3·6H2O were slowly added, and the mixture was stirred continuously for 20 hours to obtain a transparent aluminum zirconium yttrium sol. After aging for a period of time, a 15wt.% PVP solution was added. The aluminum zirconium yttrium sol and PVP solution were mixed at a ratio of 1:0.08 to obtain the precursor spinning solution.

[0103] (2) Preparation of continuous alumina nanofiber yarn precursor

[0104] The precursor spinning solution obtained in step (1) is electrospun using a single positive electrode. The spinning electrode voltage is 11kV, the injection pump flow rate is 0.5ml / h, and the rotation speed of the spinning collector is 60r / min. The spun alumina nanofiber yarn is collected by a bundling guide wheel and a yarn collection device. The collected alumina nanofiber yarn is uniform and continuous.

[0105] (3) Sintering of alumina nanofiber yarns

[0106] The continuous alumina nanofiber yarn precursor prepared in step (2) is fed into a segmented high-temperature furnace for sintering through a fiber winding system. The constant temperature zone is divided into three sections: 300℃, 800℃, and 1400℃. The working speed of the winding system is 0.15m / min, and the tension is 50cN.

[0107] The obtained alumina nanofiber yarn has a diameter of 380 μm, a linear density of 55 tex, a single fiber diameter of 450 nm to 600 nm, and a breaking strength of 176 cN.

[0108] Example 6

[0109] (1) Preparation of precursor spinning solution

[0110] 150g of Al(NO3)3·9H2O and 250g of aluminum isopropoxide were dissolved in 600ml of deionized water. The pH of the solution was adjusted to 2.0 with an appropriate amount of acetic acid. 200g of zirconium sol and 6.0g of Y(NO3)3·6H2O were slowly added under a 60℃ water bath. The equivalent ZrO2 content in the zirconium sol was 10%. The mixture was stirred continuously for 20h to obtain a transparent aluminum-zirconium-yttrium sol. After aging for a period of time, a 15wt.% PVP solution was added. The aluminum-zirconium-yttrium sol and PVP solution were mixed at a ratio of 1:0.08 to obtain the precursor spinning solution.

[0111] (2) Preparation of continuous alumina nanofiber yarn precursor

[0112] Same as Example 5.

[0113] (3) Sintering of alumina nanofiber yarns

[0114] Same as Example 5.

[0115] The obtained alumina nanofiber yarn has a diameter of 460 μm, a linear density of 57 tex, a single fiber diameter of 450 nm to 600 nm, and a breaking strength of 203 cN.

[0116] Example 7

[0117] (1) Preparation of precursor spinning solution

[0118] Dissolve 150g Al(NO3)3·9H2O and 250g aluminum isopropoxide in 600ml deionized water. Adjust the pH of the solution to 2.0 with an appropriate amount of acetic acid. Slowly add 200g zirconium magnesium sol and ZrO under a 60℃ water bath. 2、 The molar ratio of MgO is (1:0.064), and the ZrO in the zirconium magnesium sol... 2、 The total equivalent content of MgO was 10%, and a transparent aluminum-zirconium-magnesium sol was obtained by continuous stirring for 20 hours. After aging for a period of time, a 10 wt.% PVA solution was added, and the aluminum-zirconium-magnesium sol and PVA solution were mixed at a ratio of 1:0.1 to obtain the precursor spinning solution.

[0119] (2) Preparation of continuous alumina nanofiber yarn precursor

[0120] The precursor spinning solution obtained in step (1) is electrospun using a single positive electrode. The spinning electrode voltage is 15kV, the injection pump flow rate is 0.5ml / h, and the rotation speed of the spinning collector is 80r / min. The spun alumina nanofiber yarn is collected by a bundle guide wheel and a yarn collection device. The collected alumina nanofiber yarn is uniform and continuous.

[0121] (3) Sintering of alumina nanofiber yarns

[0122] The continuous alumina nanofiber yarn precursor prepared in step (2) is fed into a segmented high-temperature furnace for sintering through a fiber winding system. The constant temperature zone is divided into four sections: 300℃, 800℃, 1050℃ and 1400℃. The working speed of the winding system is 0.2m / min and the tension is 40cN.

[0123] The obtained alumina nanofiber yarn has a diameter of 410 μm, a linear density of 55 tex, a single fiber diameter of 200 nm to 350 nm, and a breaking strength of 123 cN.

[0124] Comparative Example 1

[0125] The other conditions were the same as in Example 1, except that the obtained continuous alumina nanofiber yarn was placed in a muffle furnace for sintering. The temperature was increased to 150°C at 1°C / min and held for 30 min, then increased to 400°C at 1°C / min and held for 30 min, then increased to 850°C at 5°C / min and held for 30 min, then increased to 1100°C at 10°C / min and held for 10 min, and finally increased to 1400°C at 10°C / min and held for 5 min.

[0126] Due to the lack of stretching effect from the fiber winding system, constant tension was not achieved. The uneven shrinkage of the alumina nanofiber yarn resulted in a relatively curved and loose yarn. The diameter of the obtained alumina nanofiber yarn was 620 μm, and the breaking strength of the yarn was relatively low, only 60 cN.

[0127] Comparative Example 2

[0128] The other conditions are the same as in Example 1, except that: electrospinning is performed by placing the positive and negative electrodes opposite each other, the voltages of the positive and negative electrodes are 11kV and -9kV respectively, the flow rate of the positive electrode injection pump is 0.6ml / h, and the flow rate of the negative electrode injection pump is 0.4ml / h.

[0129] Due to factors such as mutual interference of electric fields and instability of spinning jets, the uniformity of alumina nanofiber yarn precursors is poor, and filament breakage is prone to occur, making continuous spinning impossible.

[0130] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing an alumina nanofiber yarn, characterized by, The method comprises: obtaining a precursor spinning solution; electrospinning the precursor spinning solution in a single electrode mode to make the electric field distribution between a needle and a yarn collector uniform, and obtaining an alumina nanofiber yarn raw filament; segmented continuous sintering the alumina nanofiber yarn raw filament under the action of a constant tension in a winding mode, so that the nanofiber yarn raw filament uniformly shrinks under the drafting action of the constant tension, and obtaining an alumina nanofiber yarn; the single electrode mode is a single positive electrode mode or a single negative electrode mode; when the single positive electrode mode is used, the electrode process parameters include: a spinning electrode voltage of 9kV~20kV, an injection pump flow rate of 0.1ml / h~1.5ml / h, and a rotating yarn collector speed of 10r / min~200r / min; when the single negative electrode mode is used, the electrode process parameters include: a spinning electrode voltage of (-9)kV~(-20)kV, an injection pump flow rate of 0.1ml / h~1.5ml / h, and a rotating yarn collector speed of 10r / min~200r / min; the constant tension is 10cN~200cN, and the winding speed is 0.01m / min~10m / min; the segmented continuous sintering is composed of five constant temperature zones, the A temperature zone temperature is 100~300℃, the B temperature zone temperature is 300~600℃, the C temperature zone temperature is 600~900℃, the D temperature zone temperature is 900~1200℃, and the E temperature zone temperature is 1200~1600℃; the performance of the alumina nanofiber yarn includes at least one of the following: a linear density of 30tex~100tex, a yarn diameter of 100μm~600μm, a single fiber diameter of 100nm~800nm, and a breaking strength of 50cN~300cN.

2. The method of claim 1, wherein, when the single positive electrode mode is used, the spinning electrode voltage is 11kV~15kV, the injection pump flow rate is 0.3ml / h~0.8ml / h, and the rotating yarn collector speed is 30r / min~100r / min.

3. The method of claim 1, wherein, the constant tension is 10cN~100cN.

4. The method of claim 1, wherein, the method for obtaining the precursor spinning solution comprises: chemically reacting an aluminum source and an oxide source to obtain a precursor spinning sol; aging the precursor spinning sol, and then mixing the precursor spinning sol with a spinning aid to obtain the precursor spinning solution.

5. An alumina nanofiber yarn, characterized by, the alumina nanofiber yarn is prepared by the method of any one of claims 1~4.

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