CN108570725A - A kind of melt spinning raw material of aluminium oxide continuous fiber, preparation method and aluminium oxide continuous fiber obtained - Google Patents

Abstract

The invention relates to a raw material for melt spinning of alumina continuous fiber, its preparation method and the prepared alumina continuous fiber. Including: 1) Put the polyaluminoxane in the reaction kettle, heat to 60-100°C, distill under reduced pressure, continue to heat up to 110-140°C, keep warm, and finally heat up to 150-200°C, take samples to measure the softening point to reach When the target softening point is reached, stop heating and cool down to room temperature to obtain the solid alumina precursor PAO-P; 2) Mix the dispersant, aluminum-containing powder and solvent in a mass ratio of 1:(1.5～4):(3～6) Mixing and grinding to obtain a powder slurry; 3) mixing the obtained precursor with the obtained powder slurry, raising the temperature to 150-200° C. and distilling under reduced pressure to obtain a melt spinning raw material. The method synthesizes the melt-spinnable alumina precursor PAO-P, and provides the alumina fiber precursor melt spinning and sintering process, which overcomes the defect that the alumina continuous fiber cannot be prepared by melt spinning.

Description

A kind of melt-spinning raw material of alumina continuous fiber, its preparation method and prepared Alumina continuous fiber

technical field

The invention belongs to the field of preparation of ceramic fibers, in particular, relates to the preparation of inorganic oxide ceramic fibers, in particular to a melt spinning raw material of alumina continuous fibers, its preparation method and the prepared alumina continuous fibers.

Background technique

Alumina fiber is a high-performance inorganic fiber. It is mainly composed of Al ₂ O ₃ , and some also contain other metal oxides such as ZrO ₂ and SiO ₂ , etc., and has various forms such as long fibers, short fibers, and whiskers. The outstanding advantages of alumina fiber are high strength, high modulus, and excellent mechanical properties in an air atmosphere of 1000-1200 ° C. At the same time, it also has the advantages of small thermal conductivity, low thermal expansion coefficient, and good thermal shock resistance. In addition, compared with other high-performance inorganic fibers such as silicon carbide fibers, the raw material cost of alumina fibers is low, and the production process is simple, so it has huge market prospects in the fields of aerospace and civil high-end materials.

Alumina ceramics have a high melting point and low viscosity after melting, so they cannot be produced by the traditional fusion drawing process. For this reason, researchers from various countries have successively developed several different production routes by using chemical methods, among which the precursor method is the main method for the industrial production of continuous alumina fibers. According to the different types of precursor raw materials, it can be divided into organic fiber impregnation method, inorganic salt method, sol-gel method, organic polymer precursor method and mud solution method. 3M Company adopts the sol-gel method, using crystalline aluminum chloride, acetic acid, aluminum powder, deionized water, etc. as raw materials, and undergoes multi-step reactions to form a viscous hydrosol whose main body is basic aluminum chloride. The prepared spinnable colloid is dried by continuous dry spinning to form a precursor precursor, and the crystallization direction and speed are controlled by continuous heat treatment, and converted into oxide fibers (H.G.Sowman in'Sol-Gel Technology for Thin Films, Fibers, Preforms , Electronics, and Specialty Shapes' (edited by L.C. Klein), Noyes, Park Ridge, NJ, U.S.A, 1988, p.140). The disadvantage of dry spinning is that the solvent volatilization caused by solution spinning and then drying leads to environmental pollution, and the solvent volatilization process is greatly affected by ambient temperature and humidity, and the quality of the raw silk is not easy to control. The melt spinning process avoids the use of solvents and fundamentally solves the above problems, so it has become the preferred spinning process in the chemical fiber industry.

EIDu Pont Company adopts the slurry solution method, using α-Al ₂ O ₃ powder with a particle size of <500nm as the main raw material, and the Al ₂ (OH) ₅ Cl 2H ₂ O aqueous solution as the rheological additive. After melt-spinning, aging, and cracking 1. The alumina continuous fiber with a diameter of 20um and a grade of FP is obtained through ceramicization. Because the fiber is relatively thick, the mechanical properties are not as good as the level of 3M Company (ALUMINA FIBER～US 3,808,015).

At present, only the industrial production of alumina fiber cotton can be realized in China. The temperature resistance of the product is only 800°C. The development of continuous fiber is still in the laboratory research stage. Shandong University uses aluminum chloride, aluminum nitrate and aluminum isopropoxide as raw materials. Alumina continuous fiber (CN2012140454976.7) was prepared by sol-gel method. The performance of the product is close to the level of foreign mid-end products. Due to the limitation of the synthesis method, the residual sodium and potassium ions in the fiber affect the high temperature mechanical properties of the fiber.

Melt spinning is a spinning method in which raw materials are heated and melted, extruded through spinneret holes, cooled and solidified in air to form fibers. The method has the advantages of simple equipment requirements, no solvent, little pollution and good working environment. However, due to the strong metallicity of Al atoms, it is difficult to prepare alumina precursors that can be melted. Therefore, there is no report on the preparation of alumina fibers by melt spinning of precursors. However, alumina ceramics have a high melting point and a high melt viscosity. Low, so it cannot be produced by traditional fusion drawing method like quartz fiber.

In view of the above reasons, the present invention is proposed.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and provide a spinning raw material of alumina continuous fiber, its preparation method and the prepared alumina continuous fiber.

For realizing the purpose of the present invention, the present invention adopts following technical scheme:

A preparation method of melt spinning raw materials for alumina continuous fibers, wherein the preparation method comprises the steps of:

1) Preparation of melt-spinning alumina precursor: put polyaluminoxane in a reaction kettle, heat to 60-100°C under stirring, distill under reduced pressure for 30min-3h, continue to heat up to 110-140°C, and keep warm for 30min ～3h, and finally increase the temperature to 150～200℃, take a sample every 10min to measure the softening point, when the target softening point is reached, stop heating, lower to room temperature under the protection of nitrogen, and obtain the melt-spinnable solid alumina precursor PAO-P;

2) Preparation of powder slurry: mixing dispersant, aluminum-containing powder and solvent at a mass ratio of 1:(1.5-4):(3-6), and grinding to obtain powder slurry;

3) Preparation of melt spinning raw materials: uniformly mix the precursor obtained in step 1) with the powder slurry obtained in step 2) at a mass ratio of 100:0 to 15:85, preferably 80:20 to 30:70, and then Raise the temperature to 150-200° C. and distill under reduced pressure for 20 minutes to 2 hours to obtain the raw material for melt spinning.

The polyaluminoxane (PAO) used in the present invention is purchased from Suzhou Tuna Materials Co., Ltd., and the specific synthesis method can be found in patent CN201610066594.5. The activity in the molecular chain of polyaluminoxane is further polymerized by vacuum distillation, polymerization and other processes. functional groups to increase its molecular weight and softening point to obtain a solid alumina precursor with good spinning properties.

Melt spinning is a spinning method in which raw materials are heated and melted, extruded through spinneret holes, and cooled and solidified in the air to form fibers. It has the advantages of simple equipment requirements, no solvent, less pollution and good working environment. Alumina ceramics have a high melting point and low melt viscosity, so they cannot be produced by traditional melting and drawing methods like quartz fibers. And because Al atoms have strong metallicity, it is difficult to prepare alumina precursors that can be melted, so there is no report on the preparation of alumina fibers by melt spinning precursors. The invention obtains a solid alumina precursor with good spinning performance, which overcomes the defect that the alumina continuous fiber is difficult to be prepared by a melt spinning method in the prior art.

Wherein, the target softening point described in step 1) is 80-130°C, preferably 90-125°C.

The grinding described in step 2) is put into a sand mill and grind at a frequency of 5Hz-46Hz for 2-8h.

The dispersant described in step 2) is prepared by the following method: polyaluminoxane and polyethylene glycol are refluxed in a solvent for 1-3 hours, and the solvent is removed under reduced pressure to obtain the dispersant (PAO-S).

The mass ratio of described polyaluminoxane, polyethylene glycol and solvent is 1:(0.2～1):(1～5); the molecular weight of described polyethylene glycol is 200～6000; Described solvent is One or a mixture of n-propanol, isopropanol, ethylene glycol methyl ether, and ethylene glycol ethyl ether.

In step 2), the aluminum-containing powder is a mixture of one or more of aluminum powder, glassy Al ₂ O ₃ , γ-Al ₂ O ₃ , α-Al ₂ O ₃ , and mullite. The particle size is 30nm～500nm; in step 2), the solvent is one or more of n-propanol, isopropanol, absolute ethanol, ethylene glycol methyl ether, ethylene glycol ethyl ether, toluene mixture.

The invention also provides the raw material for melt spinning of alumina continuous fiber prepared by the preparation method.

The object of the present invention is also to provide a continuous alumina fiber, which is prepared by using the melt spinning raw material described in the present invention.

The present invention further provides a method for preparing the alumina continuous fiber, which includes melt spinning, non-melting, cracking and firing.

Further, the melt spinning is as follows: the spinning raw material is placed in the spinning cylinder of the melt spinning device, heated to 150-180°C under the protection of nitrogen, and melted into a uniform melt to remove residual air bubbles Afterwards, melt spinning is carried out at 110-155°C, and the continuous alumina fiber precursors are obtained through bundling and winding.

The non-melting is as follows: the continuous alumina fiber precursor obtained in step 1) is placed in a constant temperature and humidity box, the temperature is first raised to 30-40°C, and the temperature is kept at 30-45% relative humidity for 20min-2h, and then Raise the temperature to 60-95°C, keep it warm for 10min-2h at a humidity of 60-95%, and cool to room temperature to obtain infusible fibers.

Described cracking and burning can be carried out according to the method commonly used in this field, and as a kind of preferred scheme, described cracking and burning are carried out in the following manner:

The cracking is as follows: put the non-melting fiber obtained in step 2) in a high-temperature furnace to raise the temperature to 500-800°C at 0.5-30°C/min, keep it warm for 20min-3h, and the cracking atmosphere is nitrogen, argon, helium, One or several mixtures in the air;

The firing process is as follows: the cracked fiber is heated to 1000-1800°C at a heating rate of 0.15-100°C/min for 1min-10h, and the firing atmosphere is air.

Specifically, the preparation method comprises the following steps:

1) Melt spinning: put the spinning raw material in the spinning cylinder of the melt spinning device, heat it up to 150-180°C under the protection of nitrogen, and after it is melted into a uniform melt and removes residual bubbles, it is heated at 110-180°C. Carry out melt spinning at 155°C, and obtain continuous alumina fiber precursors through bundling and collecting;

2) No melting: Place the continuous alumina fiber precursor obtained in step 1) in a constant temperature and humidity box, first raise the temperature to 30-40°C, keep it warm for 20min-2h at a relative humidity of 30-45%, and then raise the temperature to 60-95°C, keep warm at 60-95% humidity for 10min-2h, cool to room temperature to obtain infusible fibers;

3) Pyrolysis: put the non-melting fiber obtained in step 2) in a high-temperature furnace to raise the temperature to 500-800°C at 0.5-30°C/min, keep it warm for 20min-3h, and the cracking atmosphere is nitrogen, argon, helium, or air One or several mixtures of gases;

4) Firing: heat up the cracked fibers to 1000-1800°C at a heating rate of 0.15-100°C/min for 1min-10h, and the firing atmosphere is air.

The technical key of the method lies in the synthesis of the melt-spinnable solid alumina precursor PAO-P, and the melt-spinning and sintering process of alumina fiber precursors. In order to further improve the fiber strength, nano-aluminum powder and grafted modified polyaluminoxane dispersant PAO-S are added to the spinning raw material to improve the uniformity of dispersion. Another beneficial effect of the modified polyaluminoxane is to generate nano-microcrystalline alumina after cracking, which improves the overall ceramic yield of spinning raw materials and the densification degree of ceramic fibers. The preparation method of the alumina continuous fiber provided by the invention is green and environment-friendly, has stable quality, excellent high-temperature mechanical properties, and can rapidly realize large-scale industrial production of the alumina continuous fiber.

The new preparation method of alumina continuous fiber provided by the present invention realizes the melt spinning process by synthesizing the spinnable solid alumina precursor, reduces solvent pollution, improves production efficiency and fiber quality consistency, and at the same time does not contain any raw materials in the method. Containing sodium and potassium ions, it avoids chemical damage to fibers under high temperature. The use of precursors combined with aluminum-containing powders for melt spinning can effectively increase the aluminum content of fiber precursors and reduce fiber volume shrinkage and loss of mechanical properties during ceramization.

The technical characteristics of the present invention are as follows: use modified polyaluminoxane (PAO-S) as a dispersant to uniformly disperse the powder and then mix it with a high molecular weight alumina precursor (PAO-P) to prepare spinning raw materials, then Alumina fiber precursors were prepared by melt spinning. The beneficial effect of modified polyaluminoxane as a dispersant is to improve the compatibility between the precursor PAO-P and the powder, and it will generate alumina in the subsequent cracking process, which is conducive to improving the overall ceramic yield of spinning raw materials ; The spinning material is homogeneously stable and can be sealed and stored at room temperature for more than 2 years.

Another beneficial effect of the present invention is that the present invention adopts melt spinning to prepare fiber precursors, which has simple equipment, convenient operation, low cost, no pollution, and is suitable for rapid large-scale production.

Description of drawings

Fig. 1 is the SEM picture of the fiber prepared by embodiment 1;

Fig. 2 is the XRD picture of the fiber prepared in embodiment 1;

Fig. 3 a is the SEM picture of the fiber prepared in embodiment 3;

Fig. 3 b is the SEM enlarged picture of the fiber prepared in embodiment 3;

Fig. 4 is the XRD picture of the fiber prepared by embodiment 3;

Fig. 5 is the photograph of the prepared fiber of embodiment 3;

Fig. 6 is the photograph of the prepared fiber of comparative example 1;

Fig. 7 a is the macrophotograph of the fiber after the fiber obtained in Example 7 was treated at 1550° C. for 20 min;

Figure 7b is a microscopic photo of the fiber obtained in Example 7 after being treated at 1550°C for 20min;

Figure 8a is a macroscopic photo of the commercial nextel-610 fiber treated at 1550°C for 20 minutes;

Figure 8b is a microscopic photo of the commercial nextel-610 fiber treated at 1550°C for 20 minutes.

It should be noted that these drawings and text descriptions are not intended to limit the concept scope of the present invention in any way, but illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention , but not to limit the scope of the present invention.

Example 1

Preparation of alumina fiber by direct melt spinning of PAO-P without adding powder

1. Preparation of melt spinning raw materials:

Preparation of melt-spinning alumina precursor: put 500g of polyaluminoxane in a reaction kettle, heat to 80°C under stirring, distill under reduced pressure for 1h, continue to heat up to 120°C, keep warm for 1h, and finally raise the temperature to 160°C , take a sample every 10 minutes to measure the softening point, when the softening point reaches 90 ° C, stop heating, nitrogen protection down to room temperature to obtain the polymerized alumina precursor PAO-P;

2. Preparation of alumina fibers

(1) Melt spinning: put the spinning raw material in the spinning cylinder of the melt spinning device, heat it up to 150°C under the protection of nitrogen, and wait for it to melt into a uniform melt and remove residual bubbles, then carry out at 120°C Melt spinning, bundled and collected to obtain continuous alumina fiber precursors;

(2) No melting: Place the continuous alumina fiber precursor obtained in step (1) in a constant temperature and humidity box, first raise the temperature to 40°C, keep it warm for 30min at a relative humidity of 30%, and then raise the temperature to 90°C. % humidity for 20 minutes, cooled to room temperature to obtain non-melting fibers;

(3) Cracking: place the non-melting fiber obtained in step (3) in a high-temperature furnace to raise the temperature to 600°C at 1°C/min, keep it warm for 1h, and the cracking atmosphere is air;

(4) Firing: heat up the pyrolyzed fibers to 1000° C. for 20 minutes at a heating rate of 30° C./min, and the firing atmosphere is air.

Fig. 1 is the SEM photo of the obtained fiber. It can be seen from the figure that the surface of the fiber is smooth, the size is uniform, and the fiber diameter is 10-12 μm. The XRD results shown in Figure 2 show that the crystal phase composition of the fiber is γ-Al ₂ O ₃ .

Example 2

Preparation of alumina fiber by direct melt spinning of PAO-P without adding powder

1. Preparation of melt spinning raw materials:

Preparation of melt-spinning alumina precursor: put 500g of polyaluminoxane in a reaction kettle, heat to 85°C under stirring, distill under reduced pressure for 2h, continue to heat up to 140°C, keep warm for 1h, and finally raise the temperature to 170°C , take a sample every 10 minutes to measure the softening point, when the softening point reaches 120 ° C, stop heating, nitrogen protection down to room temperature to obtain the polymerized alumina precursor PAO-P;

2. Preparation of alumina fibers

(1) Melt spinning: put the spinning raw material in the spinning cylinder of the melt spinning device, heat it up to 180°C under the protection of nitrogen, and wait for it to melt into a uniform melt and remove residual bubbles, then carry out at 150°C Melt spinning, bundled and collected to obtain continuous alumina fiber precursors;

(2) No melting: Place the continuous alumina fiber precursor obtained in step (1) in a constant temperature and humidity box, first raise the temperature to 40°C, keep it warm at 40% relative humidity for 1h, then raise the temperature to 85°C, and heat it at 90°C % humidity for 30 minutes, cooled to room temperature to obtain non-melting fibers;

(3) Pyrolysis: place the non-melting fiber obtained in step (2) in a high-temperature furnace to raise the temperature to 700°C at 5°C/min, keep it warm for 2h, and the cracking atmosphere is helium;

(4) Firing: heat up the pyrolyzed fibers to 1200° C. for 10 minutes at a heating rate of 10° C./min, and the firing atmosphere is air.

The surface of the fiber is smooth, the size is uniform, the diameter of the fiber is 10-12 μm, and the crystal phase composition of the fiber is γ-Al ₂ O ₃ .

Example 3

1. Preparation of melt spinning raw materials:

(1) Preparation of melt-spinning alumina precursor: put 500g of polyaluminoxane in a reaction kettle, heat it to 80°C under stirring, distill under reduced pressure for 1h, continue to heat up to 120°C, keep it warm for 1h, and finally raise the temperature again To 180°C, take samples every 10 minutes to measure the softening point, when the softening point reaches 113°C, stop heating, nitrogen protection down to room temperature to obtain polymerized alumina precursor PAO-P;

(2) Preparation of powder slurry: polyaluminoxane (PAO) and polyethylene glycol (PEG-200) were refluxed in n-propanol for 1 h, polyaluminoxane (PAO), polyethylene glycol ( The mass ratio of PEG-200) to n-propanol is 1:0.2:1, and _the solvent is removed under reduced pressure to obtain a _dispersant (PAO-S); Alcohol was put into a sand mill with a mass ratio of 1:1.5:3 and ground for 5 hours at a frequency of 46 Hz to obtain a powder slurry;

(3) Preparation of spinning raw materials: uniformly mix the precursor obtained in step (1) with the powder slurry obtained in step (2) at a mass ratio of 70:30, then heat up to 170°C and distill under reduced pressure for 30 minutes to obtain spinning raw material;

2. Preparation of alumina fibers

(1) Melt spinning: put the spinning raw material in the spinning cylinder of the melt spinning device, heat it up to 175°C under the protection of nitrogen, and wait for it to melt into a uniform melt and remove residual bubbles, then carry out at 145°C Melt spinning, bundled and collected to obtain continuous alumina fiber precursors;

(2) Non-melting: Place the continuous alumina fiber precursor obtained in step (1) in a constant temperature and humidity box, first raise the temperature to 30°C, keep it warm for 50min at a relative humidity of 40%, and then raise the temperature to 80°C. % humidity for 10 minutes, cooled to room temperature to obtain non-melting fibers;

(3) Cracking: place the non-melting fiber obtained in step (3) in a high-temperature furnace to raise the temperature to 800°C at 10°C/min, keep it warm for 2h, and use nitrogen as the cracking atmosphere;

(4) Firing: heat up the pyrolyzed fibers to 1550° C. for 20 minutes at a heating rate of 10° C./min, and the firing atmosphere is air.

Figure 3a and Figure 3b are SEM photos and SEM enlarged photos of the obtained fibers. It can be seen from the figures that the fiber surface is smooth, the size is uniform, the particle size is less than 500nm, and the fiber diameter is 10-12 μm. The XRD results shown in Fig. 4 show that the crystal phase composition of the fiber is α-Al ₂ O ₃ .

Example 4

1. Preparation of melt spinning raw materials:

(1) Preparation of melt-spinning alumina precursor: put 500g of polyaluminoxane in a reaction kettle, heat to 80°C under stirring, distill under reduced pressure for 1 hour, continue to heat up to 110°C, keep warm for 3 hours, and continue to heat up to After 180°C, samples were taken every 10 minutes to measure the softening point. When the softening point reached 120°C, the heating was stopped, and nitrogen protection dropped to room temperature to obtain the polymerized alumina precursor PAO-P;

(2) Preparation of powder slurry: polyaluminoxane (PAO) and polyethylene glycol (PEG-2000) were refluxed in isopropanol for 2 hours, polyaluminoxane (PAO), polyethylene glycol ( The mass ratio of PEG-2000) and isopropanol is 1:0.3:5, decompression solvent removal obtains dispersant (PAO-S); The dispersant, particle diameter are the mullite powder of 258nm and ethylene glycol ether Put it into a sand mill with a mass ratio of 1:2:4 and grind for 8 hours at a frequency of 30 Hz to obtain a powder slurry;

(3) Preparation of spinning raw materials: uniformly mix the precursor obtained in step (1) with the powder slurry obtained in step (2) at a mass ratio of 50:50, then heat up to 180°C and distill under reduced pressure for 20 minutes to obtain spinning raw material;

2. Preparation of alumina fibers

(1) Melt spinning: put the spinning raw material in the spinning cylinder of the melt spinning device, heat it up to 180°C under the protection of nitrogen, and wait for it to melt into a uniform melt and remove residual bubbles, then carry out at 155°C Melt spinning, bundled and collected to obtain continuous alumina fiber precursors;

(2) No melting: Place the continuous alumina fiber precursor obtained in step (1) in a constant temperature and humidity box, first raise the temperature to 35°C, keep it warm for 60min at a relative humidity of 45%, then raise the temperature to 90°C, and heat it at 60°C. % humidity for 20 minutes, cooled to room temperature to obtain non-melting fibers;

(3) Cracking: place the non-melting fiber obtained in step (3) in a high-temperature furnace to raise the temperature to 650°C at 20°C/min, keep it warm for 3h, and the cracking atmosphere is air;

(4) Firing: heat up the pyrolyzed fibers to 1400° C. for 2 hours at a heating rate of 0.5° C./min, and the firing atmosphere is air.

Example 5

1. Preparation of melt spinning raw materials:

(1) Preparation of melt-spinning alumina precursor: put 500g of polyaluminoxane in a reaction kettle, heat to 60°C under stirring, distill under reduced pressure for 3 hours, continue to heat up to 140°C, keep warm for 30min, and continue to heat up to After 150°C, samples were taken every 10 minutes to measure the softening point. When the softening point reached 110°C, the heating was stopped, and nitrogen protection dropped to room temperature to obtain the polymerized alumina precursor PAO-P;

(2) Preparation of powder slurry: polyaluminoxane (PAO) and polyethylene glycol (PEG-6000) were refluxed in ethylene glycol ether for 2.5 hours, polyaluminoxane (PAO), polyethylene glycol The mass ratio of alcohol (PEG-6000) to ethylene glycol ether is 1:0.8:4, and the solvent is removed under reduced pressure to obtain a dispersant (PAO-S); the dispersant, γ-Al ₂ O ₃ powder with a particle size of 50nm The solid and ethylene glycol methyl ether are put into a sand mill with a mass ratio of 1:4:6 and ground for 2 hours at a frequency of 20 Hz to obtain a powder slurry;

(3) Preparation of spinning raw materials: uniformly mix the precursor obtained in step (1) with the powder slurry obtained in step (2) at a mass ratio of 20:80, then heat up to 150°C and distill under reduced pressure for 2 hours to obtain spinning raw material;

2. Preparation of alumina fibers

(1) Melt spinning: put the spinning raw material in the spinning cylinder of the melt spinning device, heat it up to 150°C under the protection of nitrogen, and wait for it to melt into a uniform melt and remove residual bubbles, then carry out at 110°C Melt spinning, bundled and collected to obtain continuous alumina fiber precursors;

(2) No melting: Place the continuous alumina fiber precursor obtained in step (1) in a constant temperature and humidity box, first raise the temperature to 30°C, keep it warm for 40min at a relative humidity of 35%, then raise the temperature to 60°C, and heat it at 85°C. % humidity for 2 hours, cooled to room temperature to obtain non-melting fibers;

(3) Cracking: place the non-melting fiber obtained in step (3) in a high-temperature furnace to raise the temperature to 800°C at 0.5°C/min, keep it warm for 20min, and the cracking atmosphere is argon;

(4) Firing: heat up the pyrolyzed fibers to 1800° C. for 1 min at a heating rate of 30° C./min, and the firing atmosphere is air.

Example 6

1. Preparation of melt spinning raw materials:

(1) Preparation of melt-spinning alumina precursor: put 500g of polyaluminoxane in a reaction kettle, heat to 100°C under stirring, distill under reduced pressure for 30min, continue to heat up to 125°C, keep warm for 2h, and continue to heat up to After 200°C, take a sample every 10 minutes to measure the softening point. When the softening point reaches 125°C, stop heating, and lower it down to room temperature under nitrogen protection to obtain the polymerized alumina precursor PAO-P;

(2) Preparation of powder slurry: polyaluminoxane (PAO) and polyethylene glycol (PEG-6000) were refluxed in ethylene glycol methyl ether for 3 hours, polyaluminoxane (PAO), polyethylene glycol The mass ratio of alcohol (PEG-6000) to ethylene glycol methyl ether is 1:0.4:2, and the solvent is removed under reduced pressure to obtain a dispersant (PAO-S); the dispersant, γ-Al ₂ O ₃ with a particle size of 30nm Put the powder and ethylene glycol methyl ether in a sand mill at a mass ratio of 1:4:6 and grind for 4 hours at a frequency of 5 Hz to obtain a powder slurry;

(3) Preparation of spinning raw materials: uniformly mix the precursor obtained in step (1) with the powder slurry obtained in step (2) at a mass ratio of 15:85, then heat up to 200°C and distill under reduced pressure for 1.5h to obtain spinning silk raw material;

2. Preparation of alumina fibers

(1) Melt spinning: put the spinning raw material in the spinning cylinder of the melt spinning device, heat it up to 160°C under the protection of nitrogen, and wait for it to melt into a uniform melt and remove residual bubbles, then carry out at 130°C Melt spinning, bundled and collected to obtain continuous alumina fiber precursors;

(2) Non-melting: Place the continuous alumina fiber precursor obtained in step (1) in a constant temperature and humidity box, first raise the temperature to 30°C, keep it warm for 20min at a relative humidity of 35%, then raise the temperature to 95°C, and heat it at 95°C % humidity for 45 minutes, cooled to room temperature to obtain non-melting fibers;

(3) Pyrolysis: place the non-melting fiber obtained in step (3) in a high-temperature furnace to raise the temperature to 500°C at 30°C/min, keep it warm for 1h, and the cracking atmosphere is argon;

(4) Firing: heat up the pyrolyzed fibers to 1000° C. for 10 h at a heating rate of 0.15° C./min, and the firing atmosphere is air.

Example 7

1. Preparation of melt spinning raw materials:

(1) Preparation of melt-spinning alumina precursor: put 500g of polyaluminoxane in a reaction kettle, heat to 60°C under stirring, distill under reduced pressure for 3 hours, continue to heat up to 140°C, keep warm for 30min, and continue to heat up to After 200°C, take a sample every 10 minutes to measure the softening point. When the softening point reaches 130°C, stop heating, and lower it down to room temperature under nitrogen protection to obtain a polymerized alumina precursor PAO-P;

(2) Preparation of powder slurry: polyaluminoxane (PAO) and polyethylene glycol (PEG-6000) were refluxed in n-propanol for 1.5h, polyaluminoxane (PAO), polyethylene glycol The mass ratio of (PEG-6000) to n-propanol is 1:0.5:3, and the solvent is removed under reduced pressure to obtain a dispersant (PAO-S); the dispersant, γ-Al ₂ O ₃ powder with a particle size of 500nm and Put toluene into a sand mill with a mass ratio of 1:3.5:5 and grind for 6 hours at a frequency of 15 Hz to obtain a powder slurry;

(3) Preparation of spinning raw materials: uniformly mix the precursor obtained in step (1) with the powder slurry obtained in step (2) at a mass ratio of 25:75, then heat up to 160°C and distill under reduced pressure for 45 minutes to obtain spinning raw material;

2. Preparation of alumina fibers

(1) Melt spinning: put the spinning raw material in the spinning cylinder of the melt spinning device, heat it up to 160°C under the protection of nitrogen, and wait for it to melt into a uniform melt and remove residual bubbles, then carry out at 115°C Melt spinning, bundled and collected to obtain continuous alumina fiber precursors;

(2) No melting: Place the continuous alumina fiber precursor obtained in step (1) in a constant temperature and humidity box, first raise the temperature to 30°C, keep it warm for 2 hours at a relative humidity of 35%, then raise the temperature to 60°C, and heat it at 85°C. % humidity for 2 hours, cooled to room temperature to obtain non-melting fibers;

(3) Pyrolysis: place the non-melting fiber obtained in step (3) in a high-temperature furnace to raise the temperature to 750°C at 15°C/min, keep it warm for 1.5h, and the cracking atmosphere is argon;

(4) Firing: heat up the pyrolyzed fibers to 1300° C. for 1 min at a heating rate of 100° C./min, and the firing atmosphere is air.

Example 8

1. Preparation of melt spinning raw materials:

(1) Preparation of melt-spinning alumina precursor: put 500g of polyaluminoxane in a reaction kettle, heat to 60°C under stirring, distill under reduced pressure for 3 hours, continue to heat up to 140°C, keep warm for 30min, and continue to heat up to After 150°C, take a sample every 10 minutes to measure the softening point. When the softening point reaches 80°C, stop heating, and lower it down to room temperature under nitrogen protection to obtain the polymerized alumina precursor PAO-P;

(2) Preparation of powder slurry: polyaluminoxane (PAO) and polyethylene glycol (PEG-6000) were refluxed in n-propanol for 2.5 hours, polyaluminoxane (PAO), polyethylene glycol The mass ratio of (PEG-6000) to n-propanol is 1:1:5, and the solvent is removed under reduced pressure to obtain a dispersant (PAO-S); the dispersant, aluminum powder with a particle size of 50nm and absolute ethanol are 1:4:6 was put into a sand mill and ground for 2 hours at a frequency of 20Hz to obtain a powder slurry;

(3) Preparation of spinning raw materials: uniformly mix the precursor obtained in step (1) with the powder slurry obtained in step (2) at a mass ratio of 80:20, then heat up to 150°C and distill under reduced pressure for 2 hours to obtain spinning raw material;

2. Preparation of alumina fibers

(1) Melt spinning: put the spinning raw material in the spinning cylinder of the melt spinning device, heat it up to 150°C under the protection of nitrogen, and wait for it to melt into a uniform melt and remove residual bubbles, then carry out at 110°C Melt spinning, bundled and collected to obtain continuous alumina fiber precursors;

(2) No melting: Place the continuous alumina fiber precursor obtained in step (1) in a constant temperature and humidity box, first raise the temperature to 30°C, keep it warm for 40min at a relative humidity of 35%, then raise the temperature to 60°C, and heat it at 85°C. % humidity for 2 hours, cooled to room temperature to obtain non-melting fibers;

(3) Cracking: place the non-melting fiber obtained in step (3) in a high-temperature furnace to raise the temperature to 800°C at 0.5°C/min, keep it warm for 20min, and the cracking atmosphere is argon;

(4) Firing: heat up the pyrolyzed fibers to 1800° C. for 1 min at a heating rate of 30° C./min, and the firing atmosphere is air.

Example 9

1. Preparation of melt spinning raw materials:

(1) Preparation of melt-spinning alumina precursor: put 500g of polyaluminoxane in a reaction kettle, heat to 80°C under stirring, distill under reduced pressure for 1 hour, continue to heat up to 110°C, keep warm for 3 hours, and continue to heat up to After 180°C, samples were taken every 10 minutes to measure the softening point. When the softening point reached 120°C, the heating was stopped, and nitrogen protection dropped to room temperature to obtain the polymerized alumina precursor PAO-P;

(2) Preparation of powder slurry: polyaluminoxane (PAO) and polyethylene glycol (PEG-2000) were refluxed in isopropanol for 2 hours, polyaluminoxane (PAO), polyethylene glycol ( The mass ratio of PEG-2000) and isopropanol is 1:0.2:1, and the desolventization under reduced pressure obtains dispersant (PAO-S); The dispersant, particle diameter are the glass state Al of _258nm O ₃ and isopropanol Put it into a sand mill with a mass ratio of 1:2:4 and grind for 8 hours at a frequency of 30 Hz to obtain a powder slurry;

(3) Preparation of spinning raw materials: uniformly mix the precursor obtained in step (1) with the powder slurry obtained in step (2) at a mass ratio of 50:50, then heat up to 180°C and distill under reduced pressure for 20 minutes to obtain spinning raw material;

2. Preparation of alumina fibers

(1) Melt spinning: put the spinning raw material in the spinning cylinder of the melt spinning device, heat it up to 180°C under the protection of nitrogen, and wait for it to melt into a uniform melt and remove residual bubbles, then carry out at 155°C Melt spinning, bundled and collected to obtain continuous alumina fiber precursors;

(2) No melting: Place the continuous alumina fiber precursor obtained in step (1) in a constant temperature and humidity box, first raise the temperature to 35°C, keep it warm for 60min at a relative humidity of 45%, then raise the temperature to 90°C, and heat it at 60°C. % humidity for 20 minutes, cooled to room temperature to obtain non-melting fibers;

(3) Cracking: place the non-melting fiber obtained in step (3) in a high-temperature furnace to raise the temperature to 650°C at 20°C/min, keep it warm for 3h, and the cracking atmosphere is air;

(4) Firing: heat up the pyrolyzed fibers to 1400° C. for 2 hours at a heating rate of 0.5° C./min, and the firing atmosphere is air.

Comparative example 1

In order to illustrate the technical effect of the modified polyaluminoxane PAO-S as a dispersant, the present invention has done the following comparative experiments: the PAO-S in Example 3 is replaced with commonly used polyethylene glycol (PEG-200) as a dispersant agent; other conditions remain unchanged.

It was found that the dispersion of the powder in the prepared spinning raw material was very uneven, and the agglomerated powder could easily block the spinneret holes and cause broken filaments during the spinning process.

The scanning electron micrographs of the fiber precursors obtained in Example 3 and Comparative Example 1 are shown in Figure 5 and Figure 6. It can be seen from the figures that after the dispersant is changed from PAO-S to PEG-200, powdery particles appear in the fiber precursors. area of accumulation.

Table 1 has provided the ceramic yield of the spinning raw material of embodiment and comparative example, it can be seen that the introduction of powder slurry can greatly improve the ceramic yield of spinning raw material, it can be seen from comparative example 3 and comparative example 1 The use of PAO-S as a dispersant is beneficial to increase the ceramic yield of spinning raw materials.

The ceramic yield of the spinning raw material prepared by table 1, embodiment

specific embodiment Ceramic yield of spinning raw material Example 1 30.2% Example 2 32.8% Example 3 39.0% Example 4 45.8% Example 5 64.6% Example 6 69.8% Example 7 61.1% Example 8 43.6% Example 9 44% Comparative example 1 36.5%

Comparative example 2

In order to compare the high temperature resistance of the fibers prepared by this method, we put the fibers obtained in Example 7 and the commercialized nextel-610 fibers together in a muffle furnace to raise the temperature to 1550°C and keep the temperature for 20 minutes to compare the macroscopic and microscopic morphology, the results are shown in Figure 7a, Figure 7b, Figure 8a and Figure 8b, as can be seen from Figure 7a and Figure 7b, after the fiber prepared by this method is treated at 1550 ° C for 20 minutes (left), the fiber It is still relatively flexible, and the bundle can bear the weight of a 10g plastic ring. The SEM image (right) shows that the fiber is composed of densely packed hundreds of nanometer powders with uniform size; it can be seen from Figure 8a and Figure 8b, while the commercial nextel After the -610 fiber was treated at 1550°C for 20 minutes (left), the fibers became sticky and silky, and the fiber became very brittle and completely lost flexibility. The SEM image (right) shows that the fiber has different sizes from nanometers to micrometers. Grade powder is loosely accumulated. This experiment shows that the fiber prepared by the present invention is superior to the commercialized fiber in terms of high temperature resistance.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with the technology of the present invention Without departing from the scope of the technical solution of the present invention, personnel can use the technical content suggested above to make some changes or modify them into equivalent embodiments with equivalent changes. Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the solutions of the present invention.

Claims (10)

1. a kind of preparation method of the melt spinning raw material of aluminium oxide continuous fiber, which is characterized in that the preparation method packet Include following steps：

1) preparation of melt spinning type alumina precursor：Poly- aikyiaiurnirsoxan beta is placed in reaction kettle, 60~100 are heated under stirring DEG C, it is evaporated under reduced pressure 30min~3h, is continuously heating to 110~140 DEG C, 30min~3h is kept the temperature, is finally warming up to 150~200 again DEG C, per 10min, softening point is surveyed in sampling, when reaching target softening point, stops heating, nitrogen protection drops to room temperature, and obtaining can The solid alumina presoma PAO-P of melt-spun；

2) preparation of powdery pulp：By dispersant, body containing aluminium powder and solvent with mass ratio 1:(1.5~4):(3~6) are mixed It closes, grinding obtains powdery pulp；

3) preparation of melt spinning raw material：In mass ratio with the powdery pulp obtained by step 2) by the presoma obtained by step 1) 100:0~15:85 uniformly mixing, preferably 80:20~30:70, it then heats to 150~200 DEG C of vacuum distillation 20min~2h and obtains To melt spinning raw material.

2. preparation method according to claim 1, which is characterized in that target softening point described in step 1) is 80~ 130 DEG C, preferably 90~125 DEG C.

3. preparation method according to claim 1, which is characterized in that be ground to be put into sand mill described in step 2) 2~8h is ground with 5Hz~46Hz frequencies.

4. preparation method according to claim 1, which is characterized in that the dispersant described in step 2) is with the following method It is prepared：By poly- aikyiaiurnirsoxan beta and polyethylene glycol 1~3h of back flow reaction in solvent, decompression obtains dispersant except solvent.

5. preparation method according to claim 4, which is characterized in that the poly- aikyiaiurnirsoxan beta, polyethylene glycol and solvent Mass ratio is 1:(0.2~1):(1~5)；The molecular weight of the polyethylene glycol is 200~6000；The solvent is positive third The mixture of one or more of alcohol, isopropanol, ethylene glycol monomethyl ether, ethylene glycol ethyl ether.

6. preparation method according to claim 1, which is characterized in that in step 2), the body containing aluminium powder is aluminium powder, glass Glass state Al₂O₃、γ-Al₂O₃、α-Al₂O₃, mixtures one or more of in mullite, diameter of particle is 30nm~500nm；Step It is rapid 2) in, the solvent is normal propyl alcohol, isopropanol, absolute ethyl alcohol, ethylene glycol ethyl ether, ethylene glycol monomethyl ether, one kind in toluene Or several mixture.

7. a kind of melt spinning of aluminium oxide continuous fiber prepared by preparation method as described in claim 1~6 any one Raw material.

8. a kind of aluminium oxide continuous fiber, which is characterized in that the aluminium oxide continuous fiber is using described in claim 7 Melt spinning raw material is prepared.

9. a kind of preparation method of aluminium oxide continuous fiber according to any one of claims 8, which is characterized in that the preparation method packet Include melt spinning, non-fusible, cracking and firing.

10. preparation method according to claim 9,：It is characterized in that, the melt spinning is：Spinning material is set It heats up in the spinning cylinder of melt spinning device, under nitrogen protection and is heated to 150~180 DEG C, wait for that its melting is uniform melt And after removing residual bubbles, melt spinning is carried out at 110~155 DEG C, through boundling, is received silk, is obtained continuous alumina fiber precursor；

It is described non-fusible to be：Continuous alumina fiber precursor obtained by step 1) is placed in climatic chamber, is first warming up to 30~40 DEG C, 20min~2h is kept the temperature under 30~45% relative humidity, then is warming up to 60~95 DEG C, 60~95% it is wet Degree is lower to keep the temperature 10min~2h, is cooled to room temperature to obtain fusion-free fibre.