Modified heat-resistant fiber as well as preparation method and application thereof

Abstract

The invention relates to the technical field of fiber materials, in particular to a modified heat-resistant fiber and a preparation method and application thereof. The invention provides a modified heat-resistant fiber. The modified heat-resistant fiber comprises a heat-resistant fiber and whiskers coating the surface of the heat-resistant fiber, the crystal whiskers comprise aluminum metaborate crystal whiskers and / or aluminum borate crystal whiskers. According to the invention, the surface of the heat-resistant fiber is coated with the whisker, and the whisker structure increases the physical embedding of the heat-resistant fiber and the aerogel matrix, so that the interface bonding strength of the heat-resistant fiber and the aerogel matrix is improved; in addition, the introduction of boron endows the heat-resistant fiber with certain anti-radiation performance, and the functional application potential of the heat-resistant fiber is expanded.

Description

Technical Field

[0001] This invention relates to the field of fiber materials technology, and in particular to a modified heat-resistant fiber, its preparation method, and its application. Background Technology

[0002] Heat-resistant fiber-reinforced aerogel composites are widely used in numerous fields such as thermal insulation, catalysis, adsorption, and sound insulation due to their excellent temperature resistance and structural characteristics. In heat-resistant fiber-reinforced aerogel composites, the prerequisite for the heat-resistant fibers to perform their load-bearing function is the existence of suitable interfacial adhesion between them and the aerogel matrix. Currently, it is difficult to form a stable interfacial structure and strong bonding force between the surface of the heat-resistant fibers and the aerogel particles. This leads to the aerogel particles easily separating and peeling off from the fiber surface under external loads, severely limiting the mechanical strength of the aerogel composite material. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a modified heat-resistant fiber, its preparation method, and its application. The modified heat-resistant fiber provided by this invention can significantly improve the interfacial bonding strength between the heat-resistant fiber and the aerogel matrix.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The present invention provides a modified heat-resistant fiber, comprising heat-resistant fiber and whiskers coated on the surface of the heat-resistant fiber; the whiskers include aluminum metaborate whiskers and / or aluminum borate whiskers.

[0005] Preferably, the coating thickness of the whiskers is 50 nm to 10 μm.

[0006] Preferably, the heat-resistant fiber includes one or more of mullite fiber, alumina fiber, and aluminosilicate fiber.

[0007] Preferably, the diameter of the heat-resistant fiber is 5~13 μm.

[0008] This invention provides a method for preparing the modified heat-resistant fiber described above, comprising the following steps: Heat-resistant fibers are immersed in a boron carbide aqueous solution and then removed to obtain boron carbide-coated heat-resistant fibers. The heat-resistant fiber coated with boron carbide is heat-treated to obtain the modified heat-resistant fiber.

[0009] Preferably, the heat treatment temperature is 800~1200 ℃ and the time is 1~3 h.

[0010] Preferably, the concentration of the boron carbide aqueous solution is 0.5~10 mg / mL; and the impregnation temperature is 10~50 °C.

[0011] Preferably, the impregnation is performed at least once.

[0012] Preferably, before immersing the heat-resistant fiber in the boron carbide aqueous solution, the method further includes: pre-treating the heat-resistant fiber; the pre-treatment temperature is 600~900 ℃ and the time is 1~3 h.

[0013] This invention provides the application of the modified heat-resistant fiber described in the above-described scheme or the modified heat-resistant fiber prepared by the preparation method described in the above-described scheme in heat-resistant fiber reinforced aerogel composite materials.

[0014] This invention provides a modified heat-resistant fiber, comprising heat-resistant fibers and whiskers coated on the surface of the heat-resistant fibers; the whiskers include aluminum metaborate whiskers and / or aluminum borate whiskers. By coating the surface of the heat-resistant fibers with aluminum metaborate whiskers and / or aluminum borate whiskers, this invention improves the wettability of the heat-resistant fibers, making it easier for the aerogel matrix to spread and adhere to its surface (e.g., ...). Figure 7 , Figure 8 As shown in the comparison, the number of silica microspheres attached to the surface of the modified fiber increased significantly. On the other hand, the whisker structure increased its physical integration with the aerogel matrix, thereby improving the interfacial bonding strength between the heat-resistant fiber and the aerogel matrix. In addition, the introduction of boron endowed the heat-resistant fiber with certain radiation protection properties, expanding its functional application potential.

[0015] This invention provides a method for preparing the modified heat-resistant fiber described above. This invention grows aluminum metaborate whiskers and / or aluminum borate whiskers on the surface of heat-resistant fibers through impregnation and heat treatment. The process is simple, uses few raw materials, and results in uniform growth of the aluminum metaborate whiskers and / or aluminum borate whiskers. Attached Figure Description

[0016] Figure 1 SEM image of the modified alumina fibers prepared in Example 3; Figure 2 Another SEM image of the modified alumina fibers prepared in Example 3; Figure 3 The XRD pattern of the modified alumina fiber prepared in Example 3; Figure 4 SEM image of the modified alumina fibers prepared in Example 4; Figure 5 Another SEM image of the modified alumina fibers prepared in Example 4; Figure 6 The XRD pattern of the modified alumina fiber prepared in Example 4; Figure 7 SEM image of aerogel composite material prepared from alumina fibers without whiskers; Figure 8SEM image of the aerogel composite material prepared using the modified heat-resistant fiber of Example 3. Detailed Implementation

[0017] This invention provides a modified heat-resistant fiber, comprising heat-resistant fiber and whiskers coated on the surface of the heat-resistant fiber; the whiskers include aluminum metaborate whiskers (Al4B2O9) and / or aluminum borate whiskers (Al 18 B4O 33 ).

[0018] In this invention, the coating thickness of the whiskers is preferably 50 nm to 10 μm, and in specific embodiments it can be 50 nm, 500 nm, 800 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

[0019] In this invention, the heat-resistant fiber preferably includes one or more of mullite fiber, alumina fiber and aluminosilicate fiber; the diameter of the heat-resistant fiber is preferably 5~13 μm, and in specific embodiments it can be 5, 6, 7, 8, 9, 10, 11, 12 or 13 μm.

[0020] This invention improves the wettability of the aerogel matrix to the heat-resistant fiber by coating the surface of the fiber with whiskers. Furthermore, the whisker structure enhances the physical interlocking between the heat-resistant fiber and the aerogel matrix, thereby increasing the interfacial bonding strength. The introduction of boron imparts certain radiation-resistant properties to the heat-resistant fiber.

[0021] This invention provides a method for preparing the modified heat-resistant fiber described above, comprising the following steps: Heat-resistant fibers are immersed in a boron carbide aqueous solution and then removed to obtain boron carbide-coated heat-resistant fibers. The heat-resistant fiber coated with boron carbide is heat-treated to obtain the modified heat-resistant fiber.

[0022] Unless otherwise specified, all raw materials used in this invention are commercially available products well known in the art.

[0023] The present invention involves immersing heat-resistant fibers in an aqueous boron carbide solution and then removing them to obtain heat-resistant fibers coated with boron carbide.

[0024] Before impregnation, the heat-resistant fiber is preferably pretreated; the pretreatment temperature is preferably 600-900 °C, and the pretreatment time is preferably 1-3 h. In specific embodiments, the pretreatment temperature can be 600, 700, 800, or 900 °C; the pretreatment time can be 1, 2, or 3 h. In this invention, the rate of heating to the pretreatment temperature is preferably 5-50 °C / min. This invention utilizes pretreatment to remove sizing agents and other impurities from the surface of the heat-resistant fiber. After the pretreatment is completed, the fiber is preferably cooled to room temperature in the furnace.

[0025] In this invention, the concentration of the boron carbide aqueous solution is preferably 0.5~10 mg / mL, and in specific embodiments it can be 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 mg / mL. In this invention, the impregnation temperature is preferably 10~50 °C, and in specific embodiments it can be 10, 15, 20, 25, 30, 40 or 50 °C. In this invention, the impregnation time is preferably 0.1~2 h, and in specific embodiments it can be 0.1, 0.5, 1, 1.5 or 2 h. After removing the heat-resistant fiber from the boron carbide aqueous solution, this invention preferably further includes drying the obtained wet fiber to obtain heat-resistant fiber coated with boron carbide.

[0026] In this invention, the number of impregnations is preferably at least once, more preferably 1 to 10 times, and specifically 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times in the embodiments of this invention. In this invention, when the number of impregnations is multiple, it is preferable to remove and dry the fibers after the previous impregnation before the next impregnation. This invention, through impregnation, ensures that boron carbide is uniformly dispersed on the surface of the heat-resistant fiber, which is beneficial for the uniformity of the whisker structure subsequently grown.

[0027] After obtaining the boron carbide-coated heat-resistant fiber, the present invention performs heat treatment on the boron carbide-coated heat-resistant fiber to obtain the modified heat-resistant fiber.

[0028] In this invention, the heat treatment temperature is preferably 800~1200 °C, and the heat treatment time is preferably 1~3 h; in specific embodiments, the heat treatment temperature can be 800, 900, 1000, 1100, or 1200 °C; the heat treatment time can be 1, 1.5, 2, 2.5, or 3 h. In this invention, the rate of heating to the heat treatment temperature is preferably 1~20 °C / min, and in specific embodiments, it can be 1, 5, 10, 15, or 20 °C / min. In this invention, the heat treatment is preferably carried out in an air atmosphere. During the heat treatment process, boron carbide is converted into aluminum metaborate whiskers and / or aluminum borate whiskers.

[0029] In this invention, the type of whiskers is related to the conditions of the heat treatment.

[0030] After the heat treatment is completed, the present invention preferably cools the furnace to room temperature to obtain the modified heat-resistant fiber.

[0031] This invention provides the application of the modified heat-resistant fiber described in the above-described scheme or the modified heat-resistant fiber prepared by the preparation method described in the above-described scheme in heat-resistant fiber reinforced aerogel composite materials.

[0032] The present invention does not have any special requirements for the preparation method of the aerogel; any preparation method well known in the art can be used.

[0033] The modified heat-resistant fiber, its preparation method, and its application provided by the present invention will be described in detail below with reference to the embodiments. However, these should not be construed as limiting the scope of protection of the present invention.

[0034] Example 1 (1) Place aluminum silicate fiber (5 μm in diameter) in a muffle furnace and heat treat it at 600 °C for 3 h to remove the sizing agent and other impurities on the surface of the aluminum silicate fiber. The heating rate of the muffle furnace is 50 °C / min, and then it is cooled with the furnace. (2) At 50 °C, the aluminum silicate fiber was impregnated with an aqueous solution of boron carbide with a concentration of 10 mg / mL for 2 h. The fiber was then removed and placed in an oven to dry for a period of time to obtain aluminum silicate fiber coated with boron carbide. (3) Repeat step (2) 9 times on the boron carbide-coated aluminosilicate fibers; (4) The aluminum silicate fiber obtained in step (3) was placed in a muffle furnace at 800 °C for 3 h. The heating rate of the muffle furnace was 20 °C / min. After cooling with the furnace, the modified aluminum silicate fiber was obtained.

[0035] Example 2 (1) Place the mullite fiber (5 μm in diameter) in a muffle furnace and heat treat it at 800 °C for 2 h to remove the sizing agent and other impurities on the surface of the mullite fiber. The heating rate of the muffle furnace is 5 °C / min, and then it is cooled with the furnace. (2) At 10 °C, the mullite fiber was impregnated with an aqueous solution of boron carbide with a concentration of 0.5 mg / mL for 0.1 h. The fiber was then removed and placed in an oven to dry for a period of time to obtain mullite fiber coated with boron carbide. (3) The mullite fibers obtained in step (2) were placed in a muffle furnace at 1100 ℃ for 2 h and the heating rate of the muffle furnace was 1 ℃ / min. After cooling with the furnace, modified mullite fibers were obtained.

[0036] Example 3 (1) Alumina fibers (11 μm in diameter) were placed in a muffle furnace and heat-treated at 600 °C for 1 h to remove the sizing agent and other impurities on the surface of the alumina fibers. The heating rate of the muffle furnace was 10 °C / min, and then cooled with the furnace. (2) At 25 °C, the alumina fiber was impregnated with an aqueous solution of boron carbide with a concentration of 2 mg / mL for 0.5 h. The fiber was then removed and placed in an oven to dry for a period of time to obtain alumina fiber coated with boron carbide. (3) Following the method in step (2), the alumina fibers coated with boron carbide are impregnated and dried again; (4) The boron carbide-coated alumina fibers obtained in step (3) were placed in a muffle furnace at 900 °C for 1 h. The heating rate of the muffle furnace was 5 °C / min. After cooling with the furnace, modified alumina fibers were prepared with a whisker coating thickness of 800 nm.

[0037] Example 4 (1) Alumina fibers (11 μm in diameter) were placed in a muffle furnace and heat-treated at 600 °C for 1 h to remove the sizing agent and other impurities on the surface of the alumina fibers. The heating rate of the muffle furnace was 10 °C / min, and then cooled with the furnace. (2) At 15 °C, the alumina fiber was impregnated with an aqueous solution of boron carbide with a concentration of 2 mg / mL for 0.1 h. The fiber was then removed and placed in an oven to dry for a period of time to obtain alumina fiber coated with boron carbide. (3) Following the method in step (2), the alumina fibers coated with boron carbide are impregnated and dried twice more. (4) The alumina fibers coated with boron carbide obtained in step (3) were placed in a muffle furnace at 1200 °C for 1 h and the heating rate of the muffle furnace was 5 °C / min. After cooling with the furnace, the modified alumina fibers were obtained.

[0038] Structural characterization The modified alumina fibers prepared in Example 3 were observed by scanning electron microscopy (SEM) at different magnifications, and the results are as follows: Figure 1 and Figure 2 As shown. Figure 1 and Figure 2 The results show that a dense whisker layer is uniformly grown on the surface of the alumina fibers. The modified alumina fibers prepared in Example 3 were characterized by XRD, and the results are shown in [Figure 1]. Figure 3 .like Figure 3As shown, diffraction peaks of aluminum metaborate Al4B2O9 (00-029-0010) are present at 16.7°, 26.7°, 33.8°, 36.5°, and 42.3°, representing its (220), (231), (341), (600), and (422) crystal planes, respectively, indicating that the whiskers grown on the surface of Example 3 are aluminum metaborate whiskers (Al4B2O9).

[0039] The modified alumina fibers prepared in Example 4 were observed by SEM at different magnifications, and the results are as follows: Figure 4 and Figure 5 As shown. By Figure 4 and Figure 5 It can be seen that a layer of whisker structure is uniformly grown on the surface of alumina fiber.

[0040] The modified alumina fibers prepared in Example 4 were characterized by XRD, and the results are shown in the figure. Figure 6 .Depend on Figure 6 It can be seen that obvious diffraction peaks appear at 33.3°, 35.8°, 41.3°, 61.2°, and 70.8°, corresponding to aluminum borate (Al) respectively. 18 B4O 33 The (2 4 0), (1 22), (2 2 2), (3 6 2), and (5 2 2) crystal planes indicate that the whiskers grown on the surface of Example 4 are aluminum borate whiskers (Al). 18 B4O 33 ).

[0041] Performance testing Preparation of composite aerogels: Silica sol was prepared using methyltriethoxysilane as the silicon source and deionized water and anhydrous ethanol as solvents. Simultaneously, alumina fibers were mixed with the silica sol as reinforcement to prepare silica aerogel composites via the sol-gel method. Cylindrical silica aerogel composites with a diameter of 2 cm were prepared, and then compression tests were performed on them using a mechanical testing machine, with a maximum deformation of 10%.

[0042] The results showed that, compared with the aerogel composite material prepared without whisker-grown alumina fibers, the compressive strength of the aerogel composite material prepared with whisker-grown modified alumina fibers (Example 3) increased from 82 kPa to 139 kPa. This indicates that the interfacial bonding strength between the whisker-grown alumina fibers and the aerogel matrix is ​​improved, thereby enhancing the overall compressive performance.

[0043] Figure 7 and Figure 8 These are scanning electron microscope (SEM) images of the aerogel composite material prepared from alumina fibers without whiskers and the aerogel composite material prepared from modified alumina fibers with aluminum metaborate whiskers prepared in Example 3, respectively. Figure 7 and Figure 8 The results show that the wettability of the fibers is improved after whisker growth, the number of silica microspheres on the surface increases, and the fibers can be wrapped by more aerogel matrix, which is beneficial to improving the interfacial performance between alumina fibers and aerogel matrix.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A modified heat-resistant fiber, characterized in that, It includes heat-resistant fibers and whiskers coated on the surface of the heat-resistant fibers; the whiskers include aluminum metaborate whiskers and / or aluminum borate whiskers.

2. The modified heat-resistant fiber according to claim 1, characterized in that, The coating thickness of the whiskers is 50 nm to 10 μm.

3. The modified heat-resistant fiber according to claim 1, characterized in that, The heat-resistant fiber includes one or more of mullite fiber, alumina fiber, and aluminosilicate fiber.

4. The modified heat-resistant fiber according to claim 1 or 3, characterized in that, The diameter of the heat-resistant fiber is 5~13μm.

5. The method for preparing the modified heat-resistant fiber according to any one of claims 1 to 4, characterized in that, Includes the following steps: Heat-resistant fibers are immersed in a boron carbide aqueous solution and then removed to obtain boron carbide-coated heat-resistant fibers. The heat-resistant fiber coated with boron carbide is heat-treated to obtain the modified heat-resistant fiber.

6. The preparation method according to claim 5, characterized in that, The heat treatment is performed at a temperature of 800~1200 ℃ for 1~3 h.

7. The preparation method according to claim 5, characterized in that, The concentration of the boron carbide aqueous solution is 0.5~10 mg / mL; the impregnation temperature is 10~50 ℃.

8. The preparation method according to claim 5, characterized in that, The immersion is performed at least once.

9. The preparation method according to claim 5, characterized in that, Before impregnating the heat-resistant fiber in a boron carbide aqueous solution, the process further includes: pre-treating the heat-resistant fiber; the pre-treatment temperature is 600~900 ℃ and the time is 1~3 h.

10. The application of the modified heat-resistant fiber according to any one of claims 1 to 4 or the modified heat-resistant fiber prepared by the preparation method according to any one of claims 5 to 9 in heat-resistant fiber reinforced aerogel composites.

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