CN113860862A - Preparation method of low-cost mullite fiber - Google Patents
Preparation method of low-cost mullite fiber Download PDFInfo
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- CN113860862A CN113860862A CN202111339365.3A CN202111339365A CN113860862A CN 113860862 A CN113860862 A CN 113860862A CN 202111339365 A CN202111339365 A CN 202111339365A CN 113860862 A CN113860862 A CN 113860862A
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/16—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay
- C04B35/18—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay rich in aluminium oxide
- C04B35/185—Mullite 3Al2O3-2SiO2
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- C04B35/62231—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres based on oxide ceramics
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- C04B35/62245—Fibres based on silica rich in aluminium oxide
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Abstract
The invention discloses a preparation method of low-cost mullite fiber, which comprises the steps of firstly preparing an aluminum carboxylate solution; preparing a silicon additive; and mixing the aluminum carboxylate solution with the silicon additive, reacting to obtain precursor sol, and then carrying out concentration aging, spinning, heat treatment and the like to obtain the mullite fiber. The method does not generate harmful gases such as chlorine, nitrogen dioxide, sulfur dioxide and the like in the production process, has low requirement on raw materials, is easy to store, can directly use the commercially available raw materials, solves the technical problem that the commercially available aluminum hydroxide raw materials cannot prepare the spinnable mullite fiber, and has simple preparation process and environmental protection.
Description
Technical Field
The invention belongs to the field of inorganic nano material preparation, and particularly relates to a preparation method of low-cost mullite fiber.
Background
The mullite ceramic fiber is an engineering material with excellent comprehensive performance, can be used as a reinforcing component of materials such as ceramics, metals, plastics and the like, has the characteristics of high temperature resistance, corrosion resistance, high strength, good thermal shock resistance, good heat insulation performance and the like, and plays an important role in the fields of industry and aerospace.
In the prior art, a sol-gel method and an inorganic aluminum salt method are mostly adopted to prepare mullite fiber, and the preparation of precursor sol in the sol-gel method is the most critical process. In the prior art, aluminum hydroxide is also used as an aluminum source to prepare mullite fiber, but the process is complicated, the requirement on the activity of the raw material is extremely high, and the prepared mullite fiber does not have spinnability. In most processes for preparing spinnable mullite fiber, aluminum hydroxide and silica sol which are used as main raw materials must be prepared and used at the present time, so that the process flow and the preparation cost are increased, the quality requirements on the prepared aluminum hydroxide and silica sol are met, the activity of commercially available aluminum hydroxide is reduced due to long-time standing from preparation to market, and the silica-alumina sol prepared by using the aluminum hydroxide has no spinnability, so that the spinnable sol meeting the requirements cannot be prepared by using common raw materials which are sold on the same market.
The inorganic aluminum salt method is mainly to use aluminum powder and aluminum salt to prepare aluminum sol through high-temperature reflux, and then add silica sol to prepare mullite fiber, but dangerous hydrogen can be generated in the reaction process, and byproducts precipitated in the reaction process of some aluminum salts containing Cl and N can greatly pollute the environment.
Disclosure of Invention
In order to solve the technical problems, the invention utilizes the aluminum carboxylate solution prepared from commercial aluminum hydroxide and organic acid, mixes the aluminum carboxylate solution with silicon-containing additives, and obtains the spinnable mullite fiber after concentration aging, spinning, heat treatment and the like. The invention adopts the following technical scheme:
the preparation method of the low-cost mullite fiber is characterized by comprising the following steps of:
preparing an aluminum carboxylate solution in which Al is present as Al8-18OX12-27Exists in a multimeric form; wherein X is one or more of-COOH, -RCOO and-OOC-COOH;
preparing a silicon additive;
mixing the aluminum carboxylate solution with the silicon additive, reacting to obtain precursor sol, concentrating and aging to obtain spinnable mullite sol;
spinning the spinnable mullite sol to obtain mullite precursor fiber;
and (3) placing the mullite precursor fiber in a high-temperature furnace for heat treatment, then coating an organic alcohol or ester coating on the surface of the mullite precursor fiber subjected to heat treatment, and drying for 4-10 hours in a drying oven at 50-100 ℃ to obtain the mullite fiber.
Al8-18OX12-27The polymer polymerizes Al and short-chain carboxylic acid groups into long-chain aluminum carboxylates by virtue of coordination of Al and carboxylic acid groups, and the structure is the key point of sol spinnability.
Preferably, the preparing of the aluminum carboxylate solution comprises the steps of:
adding organic carboxylic acid into water at 50-80 ℃ to obtain an organic carboxylic acid solution;
adding aluminum hydroxide powder into the organic carboxylic acid solution to obtain a mixture solution;
continuously stirring and condensing and refluxing the mixture solution at 100-200 ℃, reacting for 10-30 hours, and concentrating under the conditions that the temperature is 40-100 ℃ and the vacuum degree is 0.09-0.1 MPa to remove carboxylic acid to obtain an aluminum carboxylate solution;
wherein the molar ratio of the aluminum hydroxide powder to the organic carboxylic acid is 1: 1-3.
Preferably, the organic carboxylic acid is one or more of formic acid, acetic acid, propionic acid, oxalic acid, malonic acid and citric acid.
Preferably, the method for preparing the silicon additive is as follows: mixing a silicon source and saturated monoacid in a molar ratio of 1: 1-3, performing ultrasonic dispersion for 30-60 min, and filtering and precipitating; adding a high-molecular additive into the clarified liquid, and mixing to obtain a silicon additive; wherein the amount of the high molecular auxiliary agent is 0-5% of the mass of the silicon source; the saturated monocarboxylic acid is one or more of formic acid, acetic acid and propionic acid.
Preferably, the silicon source is one or more of silica sol and liquid silica.
Preferably, the concentration aging temperature is 30-70 ℃; the vacuum degree is 0.09-0.1 MPa; the concentration and aging time is 4-8 h.
Preferably, the polymer auxiliary agent is one or more of lactic acid, glycerol, polyvinyl alcohol, polyethylene glycol, polyethylene oxide and methyl cellulose.
Preferably, the viscosity of the prepared spinnable mullite sol is 100-600 Pa.s.
Preferably, the heat treatment conditions are as follows: introducing oxygen at the room temperature of 600-750 ℃, and introducing nitrogen or air at the temperature of 600-750 ℃ to 1200-1400 ℃.
Preferably, the heat treatment comprises two stages: the first stage is to heat the temperature from room temperature to 600-750 ℃, oxygen is introduced during the heating period, and the first stage heat treatment is carried out at the temperature of 600-750 ℃; the second stage is heating from 600-750 deg.C to 1200-1400 deg.C, introducing nitrogen or air during heating, and performing the second stage heat treatment at 1200-1400 deg.C.
The invention also provides a low-cost mullite fiber made according to the method of any one of the preceding claims.
Compared with the prior art, the invention has the following beneficial effects:
the formation process of the aluminum carboxylate solution mainly comprises the reaction and polymerization of aluminum hydroxide and organic carboxylic acid, wherein three hydroxyl groups (OH) are arranged around Al in the aluminum hydroxide, the hydroxyl groups and carboxyl groups in the carboxylic acid are subjected to coupling reaction at high temperature, so that groups around the Al are changed into Al (HCOO) (RCOO) (OOC-COOH) with Al-O-C bonds, and after long-time high-temperature reflux, along with the continuous coupling of the groups around the Al, the groups around different Al are also coupled, so that-Al-O-C-O-Al-O-C-O-Al-bonds are formed, and finally Al in the aluminum carboxylate solution is Al-Al8-18OX12-27(wherein X is (HCOO) (RCOO) (OOC-COOH)), which is the basis for the spinnability of the sol. The method has no activity requirement on the used aluminum hydroxide, does not need to be prepared at present, can directly use the aluminum hydroxide sold in the market, reduces the cost of raw materials, and simplifies the preparation process.
The production process of the invention does not generate harmful gases such as chlorine, nitrogen dioxide, sulfur dioxide and the like, has low requirement on raw materials, is easy to store, can directly use the commercially available raw materials, has simple preparation process and is green and environment-friendly. As can be seen from FIG. 5, the spinnable mullite sol prepared by the invention has stable properties, good stability at room temperature, no obvious change of viscosity even if the sol is stored for 30 days, no gelation phenomenon, long-term storage, no coagulation and no deterioration.
Drawings
FIG. 1 is a nuclear magnetic resonance image of an aluminum carboxylate solution;
FIG. 2 is a diagram of a continuous ceramic fiber prepared by dry spinning mullite sol;
FIG. 3 is an infrared test chart of an aluminum carboxylate solution;
FIG. 4 is a graph of the viscosity of a mullite sol;
FIG. 5 is a plot of viscosity versus time for each example-prepared sol;
fig. 6 is a graph of the heat treatment curves of the examples.
Detailed Description
In order to better understand the technical scheme of the invention, the invention is further explained by combining the drawings and the specific embodiments in the specification.
Example 1:
adding formic acid and acetic acid into distilled water at 50 ℃, fully stirring and uniformly mixing, and then adding aluminum hydroxide powder. The molar ratio of aluminum hydroxide to formic acid and acetic acid was 1:1. Then the mixture solution reacts for 10 hours under the conditions of 100 ℃, continuous stirring and condensation reflux, and then the mixture solution is concentrated under the conditions of 40 ℃ and 0.09MPa of vacuum degree to remove carboxylic acid, thus preparing transparent aluminum carboxylate solution. Mixing liquid silicon dioxide and formic acid in a molar ratio of 1:1, performing ultrasonic dispersion for 30min, and filtering and precipitating; adding lactic acid, glycerol, polyvinyl butyral and polyvinyl alcohol into the clarified liquid, and mixing to obtain the silicon additive.
As can be seen from the nuclear magnetic resonance spectrum of the aluminum carboxylate solution of fig. 1: prepared aluminum carboxylate solution as polymer Al8- 18OX12-27Exist in the form of (1). From the infrared test chart of the aluminum carboxylate solution of FIG. 3, it can be seen that the functional group of the polymer exists in the form of a group such as (HCOO) (RCOO) (OOC-COOH).
The amount of the additive (i.e., the lactic acid, glycerin, polyvinyl butyral, polyvinyl alcohol) was 1% by mass of the silica; mixing the aluminum carboxylate solution with silicon-containing additive to obtain Al in the solution2O3、SiO2The molar ratio is 3: 2, and precursor sol is obtained after reaction. And (3) concentrating and aging the precursor sol at the temperature of 30 ℃ and the vacuum degree of 0.09MPa to obtain the spinnable mullite sol with the viscosity of 100Pa & s. From the viscosity profile of the mullite sol, from the shear rate, of FIG. 4The relationship curve of the rate and the sol viscosity shows that the mullite sol prepared by the method has normal rheological property. Spinning the spinnable mullite sol by a dry method to obtain mullite precursor fiber; then introducing oxygen at the temperature of between room temperature and 600 ℃, introducing nitrogen at the temperature of between 600 ℃ and 1200 ℃, wherein the heat treatment curve is shown in figure 6, coating organic alcohol on the surface of the mullite precursor fiber subjected to heat treatment, and drying for 4 hours in a drying oven at the temperature of 50 ℃ to obtain the mullite fiber shown in figure 2. As can be seen from the time-dependent change curve of the viscosity of the sol prepared in FIG. 5, the viscosity of the sol prepared was not significantly changed even after 30 days of storage, gelation did not occur, and the sol could be stored for a long period of time without coagulation and deterioration.
Example 2:
adding propionic acid and oxalic acid into distilled water at 65 ℃, fully stirring and uniformly mixing, and then adding aluminum hydroxide powder. The molar ratio of aluminum hydroxide to propionic acid and oxalic acid was 1:2. Then the mixture solution reacts for 20 hours under the conditions of 150 ℃, continuous stirring and condensation reflux, and then the solution is concentrated under the conditions of 70 ℃ and 0.09MPa of vacuum degree to remove carboxylic acid, thus preparing transparent aluminum carboxylate solution. As can be seen from the nuclear magnetic resonance spectrum of the aluminum carboxylate solution of fig. 1: prepared aluminum carboxylate solution as polymer Al8-18OX12-27Exist in the form of (1). From the infrared test chart of the aluminum carboxylate solution of FIG. 3, it can be seen that the functional group of the polymer exists in the form of a group such as (HCOO) (RCOO) (OOC-COOH).
Then mixing the silica sol and acetic acid in a molar ratio of 1:2, carrying out ultrasonic dispersion for 45min, and filtering and precipitating; and adding polyvinylpyrrolidone, polyethylene glycol and polyacrylic acid into the clarified liquid, and mixing to obtain the silicon additive. The amount of the added auxiliary agents (namely polyvinylpyrrolidone, polyethylene glycol and polyacrylic acid) is 3 percent of the mass of the silica sol; mixing the aluminum carboxylate solution with silicon-containing additive to obtain Al in the solution2O3、SiO2The molar ratio is 3: 2, and precursor sol is obtained after reaction. And (3) concentrating and aging the precursor sol at the temperature of 50 ℃ and the vacuum degree of 0.09MPa to obtain the spinnable mullite sol with the viscosity of 350Pa & s. Viscosity profile of mullite sol from FIG. 4And the line graph shows that the rheological property of the mullite sol prepared by the method is normal according to a relation curve of the shear rate and the sol viscosity. Spinning the spinnable mullite sol by a dry method to obtain mullite precursor fiber; then, oxygen gas was introduced at room temperature to 750 ℃ and nitrogen gas was introduced at 750 ℃ to 1400 ℃ and the treatment curve is shown in FIG. 6. And coating organic alcohol on the surface of the mullite precursor fiber subjected to heat treatment, and drying for 4 hours in a drying oven at 50 ℃ to obtain the mullite fiber shown in figure 2. As can be seen from the time-dependent change curve of the viscosity of the sol prepared in FIG. 5, the viscosity of the sol prepared was not significantly changed even after 30 days of storage, gelation did not occur, and the sol could be stored for a long period of time without coagulation and deterioration.
Example 3:
adding malonic acid and citric acid into distilled water at 80 ℃, fully stirring and uniformly mixing, and then adding aluminum hydroxide powder. The molar ratio of aluminum hydroxide to malonic acid and citric acid was 1: 3. Then the mixture solution reacts for 30 hours under the conditions of 200 ℃, continuous stirring and condensation reflux, and then the mixture solution is concentrated under the conditions of 100 ℃ and 0.1MPa of vacuum degree to remove carboxylic acid, thus preparing transparent aluminum carboxylate solution. As can be seen from the nuclear magnetic resonance spectrum of the aluminum carboxylate solution of fig. 1: prepared aluminum carboxylate solution as polymer Al8-18OX12-27Exist in the form of (1). From the infrared test chart of the aluminum carboxylate solution of FIG. 3, it can be seen that the functional group of the polymer exists in the form of a group such as (HCOO) (RCOO) (OOC-COOH).
Then mixing liquid silicon dioxide and propionic acid in a molar ratio of 1:3, ultrasonically dispersing for 60min, and filtering and precipitating; adding polyoxyethylene, methylcellulose and hydroxyethyl cellulose into the clarified liquid, and mixing; the amount of the added auxiliaries (i.e., polyethylene oxide, methyl cellulose, hydroxyethyl cellulose) was 5% by mass of the silica; the silicon-containing additive is prepared.
Mixing the aluminum carboxylate solution with silicon-containing additive to obtain Al in the solution2O3、SiO2The molar ratio is 3: 2, and precursor sol is obtained after reaction. Then the precursor sol is concentrated and aged under the conditions of 70 ℃ of temperature and 0.1MPa of vacuum degree to obtainTo a spinnable mullite sol with a viscosity of 600Pa · s. The viscosity curve of the mullite sol in FIG. 4 shows that the mullite sol prepared by the method has normal rheological property according to the relation curve between the shear rate and the sol viscosity. Spinning the spinnable mullite sol by a dry method to obtain mullite precursor fiber; then introducing oxygen at room temperature to 700 ℃, introducing nitrogen at 700 ℃ to 1300 ℃, wherein the heat treatment curve is shown in figure 6, coating the surface of the mullite precursor fiber subjected to heat treatment with organic alcohol, and finally drying in a drying oven at 100 ℃ for 10h to obtain the mullite fiber shown in figure 2. As can be seen from the time-dependent change curve of the viscosity of the sol prepared in FIG. 5, the viscosity of the sol prepared was not significantly changed even after 30 days of storage, gelation did not occur, and the sol could be stored for a long period of time without coagulation and deterioration.
Example 4:
adding acetic acid, propionic acid and oxalic acid into distilled water at 80 ℃, fully stirring and uniformly mixing, and then adding aluminum hydroxide powder. The molar ratio of aluminum hydroxide to acetic acid, propionic acid and oxalic acid was 1:2. Then the mixture solution reacts for 18 hours under the conditions of 140 ℃, continuous stirring and condensation reflux, and then the solution is concentrated under the conditions of 100 ℃ and 0.1MPa of vacuum degree to remove carboxylic acid, thus preparing transparent aluminum carboxylate solution. The nuclear magnetic resonance spectrum of the aluminum carboxylate solution in figure 1 can be seen: prepared aluminum carboxylate solution as polymer Al8-18OX12-27Exist in the form of (1). From the infrared test chart of the aluminum carboxylate solution of FIG. 3, it can be seen that the functional group of the polymer exists in the form of a group such as (HCOO) (RCOO) (OOC-COOH).
Then mixing liquid silicon dioxide and propionic acid in a molar ratio of 1:2, ultrasonically dispersing for 60min, and filtering and precipitating; adding polyoxyethylene and polyvinyl alcohol into the clarified liquid for mixing; the amount of the added auxiliaries (i.e., polyethylene oxide, polyvinyl alcohol) is 1% of the mass of the silica; the silicon-containing additive is prepared.
Mixing the aluminum carboxylate solution with silicon-containing additive to obtain Al in the solution2O3、SiO2The molar ratio is 3: 2, and precursor sol is obtained after reaction. Then the precursor sol is put at the temperature of 40 ℃,concentrating and aging under the condition that the vacuum degree is 0.1MPa to obtain the spinnable mullite sol with the viscosity of 500Pa s. The viscosity curve of the mullite sol in FIG. 4 shows that the mullite sol prepared by the method has normal rheological property according to the relation curve between the shear rate and the sol viscosity. Spinning the spinnable mullite sol by a dry method to obtain mullite precursor fiber; then introducing oxygen at room temperature to 700 ℃ and introducing nitrogen at 700 ℃ to 1300 ℃, wherein the heat treatment curve is shown in figure 6, coating the surface of the mullite precursor fiber subjected to heat treatment with organic alcohol, and drying in a drying oven at 70 ℃ for 7h to obtain the mullite fiber shown in figure 2. As can be seen from the time-dependent change curve of the viscosity of the sol prepared in FIG. 5, the viscosity of the sol prepared was not significantly changed even after 30 days of storage, gelation did not occur, and the sol could be stored for a long period of time without coagulation and deterioration.
Example 5:
adding formic acid, acetic acid and citric acid into distilled water at 80 ℃, fully stirring and uniformly mixing, and then adding aluminum hydroxide powder. The molar ratio of aluminum hydroxide to formic acid, acetic acid and citric acid was 1: 3. Then the mixture solution is reacted for 24 hours under the conditions of 120 ℃, continuous stirring and condensation reflux, and then the solution is concentrated to remove carboxylic acid under the conditions that the temperature is 80 ℃ and the vacuum degree is 0.095MPa, so as to prepare transparent aluminum carboxylate solution. As can be seen from the nuclear magnetic resonance spectrum of the aluminum carboxylate solution of fig. 1: prepared aluminum carboxylate solution as polymer Al8-18OX12-27Exist in the form of (1). From the infrared test chart of the aluminum carboxylate solution of FIG. 3, it can be seen that the functional group of the polymer exists in the form of a group such as (HCOO) (RCOO) (OOC-COOH).
Then mixing the liquid silicon dioxide with acetic acid in a molar ratio of 1:2, carrying out ultrasonic dispersion for 60min, and filtering and precipitating; adding glycerol, polyethylene glycol and polyoxyethylene into the clarified liquid, and mixing, wherein the amount of the added auxiliary agent (namely the glycerol, the polyethylene glycol and the polyoxyethylene) is 1% of the mass of the silicon dioxide; the silicon-containing additive is prepared.
Mixing the aluminum carboxylate solution with silicon-containing additive to obtain Al in the solution2O3、SiO2The molar ratio is 3: 2, and precursor sol is obtained after reaction. And then concentrating and aging the precursor sol at the temperature of 60 ℃ and the vacuum degree of 0.1MPa to obtain the spinnable mullite sol with the viscosity of 600Pa & s. The viscosity curve of the mullite sol in FIG. 4 shows that the mullite sol prepared by the method has normal rheological property according to the relation curve between the shear rate and the sol viscosity. Spinning the spinnable mullite sol by a dry method to obtain mullite precursor fiber; then introducing oxygen at the temperature of between room temperature and 700 ℃, introducing nitrogen at the temperature of between 700 and 1300 ℃, wherein the heat treatment curve is shown in figure 6, coating the ester coating on the surface of the mullite precursor fiber after heat treatment, and drying for 7 hours in a drying oven at the temperature of 70 ℃ to obtain the mullite fiber shown in figure 2. As can be seen from the time-dependent change curve of the viscosity of the sol prepared in FIG. 5, the viscosity of the sol prepared was not significantly changed even after 30 days of storage, gelation did not occur, and the sol could be stored for a long period of time without coagulation and deterioration.
Example 6:
the embodiment provides a preparation method of low-cost mullite fiber, which comprises the following steps:
preparing an aluminum carboxylate solution, wherein Al in the aluminum carboxylate solution is Al8-18OX12-27The polymer form of (A) exists, and X is one or more of-COOH, -RCOO, -OOC-COOH;
preparing a silicon additive;
mixing the aluminum carboxylate solution with a silicon additive, reacting to obtain precursor sol, and concentrating and aging to obtain spinnable mullite sol;
the spinnable mullite sol is subjected to dry spinning through a spinning system to obtain mullite precursor fiber, wherein the dry spinning is a preferable spinning method for preparing the mullite precursor fiber from the spinnable mullite sol in the embodiment, the spinning method in the embodiment is not limited to the dry spinning, a person skilled in the art can reasonably select the spinning method according to the actual working condition requirement, and a corresponding spinning system can also make corresponding selection;
placing the mullite precursor fiber in a high-temperature furnace for heat treatment, then coating an organic alcohol or ester coating on the surface of the mullite precursor fiber subjected to heat treatment, and drying for 4-10 h (for example, 4h, 5h, 6h, 7h, 8.5h, 9h and 10h) in a drying oven at 50-100 ℃ (for example, 50 ℃, 60 ℃, 80 ℃ and 100 ℃) to obtain the mullite fiber.
Specifically, in this example, an aluminum carboxylate solution was prepared by the following steps:
s1, adding the organic carboxylic acid into water with the temperature of 50-80 ℃ (for example, 50 ℃, 65 ℃, 70 ℃, 75 ℃ and 80 ℃) and fully stirring and uniformly mixing to obtain an organic carboxylic acid solution;
s2, adding aluminum hydroxide powder into the organic carboxylic acid solution to obtain a mixture solution;
s3, the mixture solution is continuously stirred and condensed and refluxed at 100 to 200 ℃ (for example, 100 ℃, 105 ℃, 120 ℃, 150 ℃, 165 ℃, 180 ℃ and 200 ℃) to react for 10 to 30 hours (for example, 10 hours, 15 hours, 18 hours, 20 hours, 25 hours, 28 hours and 30 hours can be selected), and then the carboxylic acid is concentrated and removed under the condition that the temperature is 40 to 100 ℃ (for example, 40 ℃, 50 ℃, 65 ℃, 80 ℃, 90 ℃ and 100 ℃) and the vacuum degree is 0.09 to 0.1MPa (for example, 0.09MPa, 0.095MPa and 0.1MPa), thereby obtaining the aluminum carboxylate solution.
In the present example, the molar ratio of the aluminum hydroxide powder to the organic carboxylic acid is 1:1 to 3 (for example, 1:1, 1:1.5, 1:2, 1:2.5, 1:3 may be selected) when preparing the aluminum carboxylate solution; the organic carboxylic acid is one or more of formic acid, acetic acid, propionic acid, oxalic acid, malonic acid and citric acid; the starting aluminum hydroxide powder is preferably a commercially available aluminum hydroxide.
In this example, the silicon additive was prepared by the following method: mixing a silicon source and a saturated monoacid at a molar ratio of 1: 1-3 (for example, 1:1, 1:1.5, 1:2, 1:3), ultrasonically dispersing for 30-60 min (for example, 30min, 40min, 50min, 60min), and filtering and precipitating to obtain a clear solution; and adding a high-molecular additive into the clarified liquid, and mixing to obtain the silicon additive. In this embodiment, when the silicon additive is prepared, the amount of the polymer additive is 0 to 5% (e.g., 0%, 1%, 3%, 4%, 5%) of the mass of the silicon source; the silicon source is one or more of silica sol and liquid silicon dioxide; the saturated monocarboxylic acid is one or more of formic acid, acetic acid and propionic acid; the polymer auxiliary agent is one or more of lactic acid, glycerol, polyvinyl alcohol, polyethylene glycol, polyoxyethylene and methyl cellulose.
In this example, the concentration and aging step before obtaining the spinnable mullite sol was carried out under conditions of a concentration and aging temperature of 30 to 70 ℃ (for example, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃), a vacuum degree of 0.09 to 0.1MPa (for example, 0.09MPa, 0.095MPa, 0.1MPa), and a concentration and aging time of 4 to 8 hours (for example, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours). In this example, the spinnable mullite sol obtained after the concentration and aging has a viscosity of 100 to 600Pa · s (for example, 100Pa, 200Pa, 350Pa, 400Pa, 500Pa, 600 Pa).
In this embodiment, the heat treatment conditions for placing the mullite precursor fiber in a high temperature furnace for heat treatment are as follows: introducing oxygen at the room temperature of 600-750 ℃, and introducing nitrogen or air at the temperature of 600-750 ℃ to 1200-1400 ℃. In this embodiment, preferably, the heat treatment comprises two stages: the first stage is heating from room temperature to 600-750 deg.C (for example, 600 deg.C, 650 deg.C, 700 deg.C, 750 deg.C), introducing oxygen during heating, and performing first stage heat treatment under 600-750 deg.C (for example, 600 deg.C, 650 deg.C, 700 deg.C, 750 deg.C); the second stage is to heat the substrate from 600 to 750 ℃ (e.g., 600 ℃, 650 ℃, 700 ℃, 750 ℃) to 1200 to 1400 ℃ (e.g., 1200 ℃, 1300 ℃, 1350 ℃, 1400 ℃) corresponding to the heat treatment temperature of the first stage, and to introduce nitrogen or air during the heating, and to perform the second stage heat treatment under the temperature condition of 1200 to 1400 ℃ (e.g., 1200 ℃, 1300 ℃, 1350 ℃, 1400 ℃). Preferably, when the second-stage heat treatment is performed, the gas atmosphere in the first stage is removed and nitrogen or air is introduced.
The present example also provides a low-cost mullite fiber that is prepared according to the method of preparing a low-cost mullite fiber of this example.
The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.
Claims (10)
1. The preparation method of the low-cost mullite fiber is characterized by comprising the following steps of:
preparing an aluminum carboxylate solution in which Al is present as Al8-18OX12-27Exists in a multimeric form; wherein X is one or more of-COOH, -RCOO and-OOC-COOH;
preparing a silicon additive;
mixing the aluminum carboxylate solution with the silicon additive, reacting to obtain precursor sol, concentrating and aging to obtain spinnable mullite sol;
carrying out dry spinning on the spinnable mullite sol by a spinning system to obtain mullite precursor fiber;
and (3) placing the mullite precursor fiber in a high-temperature furnace for heat treatment, then coating an organic alcohol or ester coating on the surface of the mullite precursor fiber subjected to heat treatment, and drying for 4-10 hours in a drying oven at 50-100 ℃ to obtain the mullite fiber.
2. The method of preparing a low cost mullite fiber of claim 1 wherein the preparing of the solution of aluminum carboxylate includes the steps of:
adding organic carboxylic acid into water at 50-80 ℃ to obtain an organic carboxylic acid solution;
adding aluminum hydroxide powder into the organic carboxylic acid solution to obtain a mixture solution;
continuously stirring and condensing and refluxing the mixture solution at 100-200 ℃, reacting for 10-30 hours, and concentrating under the conditions that the temperature is 40-100 ℃ and the vacuum degree is 0.09-0.1 MPa to remove carboxylic acid to obtain an aluminum carboxylate solution;
wherein the molar ratio of the aluminum hydroxide powder to the organic carboxylic acid is 1: 1-3.
3. The method of claim 2 wherein the organic carboxylic acid is one or more of formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, and citric acid.
4. The method of preparing a low cost mullite fiber of claim 1 wherein the method of preparing the silicon additive is: mixing a silicon source and saturated monoacid in a molar ratio of 1: 1-3, performing ultrasonic dispersion for 30-60 min, and filtering and precipitating; adding a high-molecular additive into the clarified liquid, and mixing to obtain a silicon additive; wherein the amount of the high molecular auxiliary agent is 0-5% of the mass of the silicon source; the saturated monocarboxylic acid is one or more of formic acid, acetic acid and propionic acid.
5. The method for preparing the low-cost mullite fiber as claimed in claim 4 wherein the silicon source is one or more of silica sol and liquid silica.
6. The method for preparing the low-cost mullite fiber as claimed in claim 4, wherein the polymer auxiliary agent is one or more of lactic acid, glycerin, polyvinyl alcohol, polyethylene glycol, polyethylene oxide and methyl cellulose.
7. The method for preparing the low-cost mullite fiber as claimed in claim 1, wherein the concentration aging temperature is 30 to 70 ℃; the vacuum degree is 0.09-0.1 MPa; the concentration and aging time is 4-8 h.
8. The method for preparing the low-cost mullite fiber according to claim 7, wherein the prepared spinnable mullite sol has a viscosity of 100-600 Pa-s.
9. The method of preparing a low cost mullite fiber of claim 1 wherein the heat treatment conditions are: introducing oxygen at the room temperature of 600-750 ℃, and introducing nitrogen or air at the temperature of 600-750 ℃ to 1200-1400 ℃.
10. A low cost mullite fiber when made according to the process of any one of claims 1 to 9.
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| CN114773070A (en) * | 2022-04-18 | 2022-07-22 | 山东大学 | Preparation method of alumina continuous fiber by using aluminum carboxylate sol as precursor |
| CN116516524A (en) * | 2023-07-04 | 2023-08-01 | 山东工业陶瓷研究设计院有限公司 | Boron-containing continuous alumina fiber and preparation method thereof |
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| CN114162844B (en) * | 2021-12-07 | 2023-06-02 | 中南大学 | Precursor composite sol for alumina/mullite biphase fiber and preparation method thereof |
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| US4047965A (en) * | 1976-05-04 | 1977-09-13 | Minnesota Mining And Manufacturing Company | Non-frangible alumina-silica fibers |
| WO1992001644A1 (en) * | 1990-07-23 | 1992-02-06 | Akzo N.V. | Aluminium oxide fibres and process for producing them |
| JP2013256404A (en) * | 2012-06-12 | 2013-12-26 | Gifu Univ | Silicon dioxide precursor sol, mullite precursor sol using the same, and method of manufacturing mullite |
| CN110004521A (en) * | 2019-02-28 | 2019-07-12 | 山东大学 | A kind of preparation method of spinnability silicon-aluminum sol |
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| US4047965A (en) * | 1976-05-04 | 1977-09-13 | Minnesota Mining And Manufacturing Company | Non-frangible alumina-silica fibers |
| WO1992001644A1 (en) * | 1990-07-23 | 1992-02-06 | Akzo N.V. | Aluminium oxide fibres and process for producing them |
| JP2013256404A (en) * | 2012-06-12 | 2013-12-26 | Gifu Univ | Silicon dioxide precursor sol, mullite precursor sol using the same, and method of manufacturing mullite |
| CN110004521A (en) * | 2019-02-28 | 2019-07-12 | 山东大学 | A kind of preparation method of spinnability silicon-aluminum sol |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114773070A (en) * | 2022-04-18 | 2022-07-22 | 山东大学 | Preparation method of alumina continuous fiber by using aluminum carboxylate sol as precursor |
| CN116516524A (en) * | 2023-07-04 | 2023-08-01 | 山东工业陶瓷研究设计院有限公司 | Boron-containing continuous alumina fiber and preparation method thereof |
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