Three-dimensional network nanowire soft interface on surface of alumina fiber and preparation method thereof

Abstract

This invention provides a three-dimensional network nanowire soft interface on the surface of alumina fibers and its preparation method, belonging to the technical field of alumina fiber-reinforced ceramic composite materials. In this invention, alumina fibers are pretreated, fixed with a clamp, and placed in a chemical vapor deposition (CVD) furnace. The furnace is evacuated and heated. After heating, the temperature is maintained while trichloromethylsilane, hydrogen, and argon are introduced for CVD. After deposition, the mixture is cooled to room temperature to obtain alumina fibers with a three-dimensional network nanowire soft interface. The presence of nanowires significantly increases the interfacial surface area between the fiber and the matrix. When an external load is applied to an oxide ceramic matrix composite material prepared from this fiber, the shear stress on the nanowire surface, widely distributed at the fiber-matrix interface, can increase the energy dissipated during composite material failure, thereby further improving the toughening effect.

Description

Technical Field

[0001] This invention belongs to the technical field of alumina fiber reinforced ceramic composite materials, and particularly relates to a three-dimensional network nanowire soft interface on the surface of alumina fibers and its preparation method. Background Technology

[0002] Oxide ceramics possess numerous excellent properties, including high temperature resistance, oxidation resistance, high strength, low density, and wear resistance. To overcome the inherent brittleness of oxide ceramics and enhance their toughness, introducing high-strength oxide ceramic fibers into the oxide ceramic matrix to form oxide ceramic matrix composites is one of the most effective methods. A significant example is alumina fiber-reinforced oxide ceramic matrix (Al2O3 / Oxide) composites. Although the development of Al2O3 / Oxide composites lags behind high-temperature alloys and non-oxide composites, they possess advantages that the latter two lack. Compared to high-temperature alloys, Al2O3 / Oxide composites have a density reduction of approximately two-thirds, resulting in lighter weight and lower fuel consumption. Compared to non-oxide composites, the inherent high-temperature oxidation resistance and water vapor corrosion resistance of Al2O3 / Oxide composites significantly improve material reliability. Furthermore, the preparation process of Al2O3 / Oxide composites is simple and inexpensive, making them environmentally friendly materials. Based on these advantages, Al2O3 / Oxide composites hold an irreplaceable position in many fields.

[0003] In Al2O3 / Oxide composites, the interface refers to the discontinuous region between the fiber reinforcement and the matrix, and it is a decisive factor in the properties of the composite. The introduction of the interfacial phase can significantly improve the performance of Al2O3 / Oxide composites. For example, it can prevent adverse chemical reactions between the fiber and the matrix, and avoid mechanical property degradation due to changes in the chemical composition of the fiber or matrix. However, its most important function is to improve the toughness of the composite. When an external load is applied to the composite, the shear stress located at the interface can increase the energy dissipated during composite failure, i.e., the toughening effect. To fully utilize this toughening mechanism, the interfacial surface area of ​​the fiber-matrix interface is a key factor. Currently, there are many types of interfacial phases used in Al2O3 / Oxide composites. For example, the most widely used weak interfacial phases include PyC (pyrolytic carbon), monolithium, ZrO2, and BN. The main function of these interfaces is to transfer loads while preventing strong interfacial bonding between the fiber and matrix during preparation and (high-temperature) service, thereby improving the material's strength retention and fracture toughness. Furthermore, porous interfacial phases, due to their low density and strength, and the fact that their microporous structure can deflect cracks and protect the fibers, are also commonly used. Other interfacial phases include escape interfacial phases and porous-matrix interfacial phases. However, these diverse interfacial phases are all in ceramic form between the fiber and matrix in composites. The inherent shape characteristics of ceramics result in a relatively small fiber-matrix bonding surface area and relatively low shear stress, which cannot meet the requirements for high-toughness Al2O3 / Oxide composites under certain specific environments.

[0004] Therefore, in order to meet the requirement of high-toughness Al2O3 / Oxide composite materials in certain specific environments, it is urgent for those skilled in the art to provide a special interfacial phase on the surface of alumina fibers and its preparation method. Summary of the Invention

[0005] To overcome the low toughness of Al2O3 / Oxide composite materials, this invention proposes a three-dimensional network nanowire soft interface on the surface of alumina fibers and its preparation method, aiming to toughen Al2O3 / Oxide composite materials. This invention uses chemical vapor deposition to deposit randomly distributed nanowires on the surface of alumina fibers. The nanowires bend, grow, and accumulate, intertwining and connecting irregularly in multiple dimensions, ultimately forming a three-dimensional network nanowire soft interface.

[0006] To achieve the above objectives, the present invention provides a method for preparing a three-dimensional network nanowire soft interface on the surface of alumina fibers, comprising the following steps:

[0007] After pretreatment, the alumina fibers are fixed with a clamp and placed in a chemical vapor deposition furnace. The furnace is evacuated and heated. After the heating is completed, the temperature is maintained and trichloromethylsilane, hydrogen and argon are introduced for chemical vapor deposition. After deposition, the alumina fibers are cooled to room temperature to obtain alumina fibers with a three-dimensional network of nanowire soft interfaces on the surface.

[0008] Furthermore, the alumina fiber includes one or more of unidirectional alumina fiber, multidirectional alumina fiber, and fiber cloth woven from alumina fiber.

[0009] Furthermore, the alumina fiber pretreatment involves high-temperature sintering of the alumina fibers to remove organic adhesives from the fiber surface. The high-temperature sintering process involves a heating rate of 400–600°C / h, a sintering temperature of 500–600°C, and a holding time of 1–3 hours.

[0010] Furthermore, the chemical vapor deposition furnace is evacuated to a vacuum level of 1–3 kPa, and the temperature is increased to 1000–1300 °C at a heating rate of 400–600 °C / h.

[0011] Furthermore, during the heating process, argon gas with a flow rate of 100–500 mL / min is introduced to form a protective atmosphere.

[0012] Furthermore, the heat preservation time is 3 to 6 hours.

[0013] Furthermore, during the heat preservation process, the flow rate of trichloromethylsilane is 0.1–0.4 g / min, the flow rate of hydrogen is 1000–3000 mL / min, and the flow rate of argon is 500–1000 mL / min.

[0014] Furthermore, after deposition is complete, the flow of trichloromethylsilane and hydrogen is stopped, and the flow rate of argon is reduced to 100–500 mL / min.

[0015] Furthermore, the clamp is a graphite clamp, with circular pores of 3-5 mm in diameter on the middle surface of the clamp, the distance between each pore being 7-10 mm, and the clamp length being 12-18 cm. Alumina fibers are placed in the middle of the graphite clamp and bound with molybdenum wire (which only serves a fixing function; other binding materials can also be used, as long as they meet the high-temperature resistance requirements). The clamp fixes the alumina fibers, thus maintaining fiber stability, and simultaneously alters the airflow direction of the furnace gas phase as it passes through the fibers. The gas phase (trichloromethylsilane and hydrogen) permeates through the clamp and accumulates on the surface of the alumina fibers, undergoing a chemical reaction to generate nanowires. The nanowires bend, grow, and accumulate, intertwining and irregularly connecting in multiple dimensions, ultimately forming a three-dimensional network of nanowire soft interfaces.

[0016] The fixture contains pores. When trichloromethylsilane and hydrogen gaseous phases flow through these pores, the geometry and size of the pores cause localized changes in the velocity and pressure of the gas phases. When these gaseous phases meet near the pores, the non-uniformity of velocity and the change in direction create vortices at the pore outlet and in the surrounding area. These vortices can increase the collision frequency and mixing efficiency between gas molecules, thereby affecting the rate and path of the chemical reaction.

[0017] The present invention also provides an alumina fiber with a three-dimensional network nanowire soft interface on the surface prepared by the above preparation method. The nanowires in the three-dimensional network nanowire soft interface on the surface of the alumina fiber have one or more structures such as spiral, curved and folded, with a length of 2 to 30 μm and a thickness of 0.5 to 10 μm.

[0018] The present invention also provides the application of alumina fibers with a three-dimensional network nanowire soft interface on the surface prepared by the above preparation method in the preparation of alumina fiber reinforced oxide ceramic matrix composites.

[0019] The forming principle of the three-dimensional network nanowire soft interface on the surface of alumina fibers in this invention is as follows:

[0020] After trichloromethylsilane enters the furnace, the high temperature promotes its decomposition, breaking carbon-silicon and silicon-chlorine bonds and releasing silicon and hydrogen chloride. Simultaneously introduced hydrogen not only acts as a reducing agent to help remove hydrogen chloride, reduce corrosion, and improve reaction purity, but also increases the reaction's effectiveness by promoting further breaking of silicon-chlorine bonds. With the aid of a vortex, gas-phase mixing and reactant contact are significantly enhanced. The vortex creates a dynamic reaction environment, improving the uniform distribution of the gas phase and accelerating the chemical reaction process. This dynamic environment promotes the further transformation of intermediates (such as methylsilane and chloromethylsilane) generated from the decomposition and reduction reactions. Under the influence of high temperature and hydrogen, the intermediates continue to decompose, releasing more free silicon and carbon atoms. These free silicon and carbon atoms rapidly nucleate on the surface of the alumina fibers, forming tiny silicon carbide nuclei. The presence of eddies not only promotes the rapid formation of crystal nuclei, but also optimizes the growth direction and rate of crystal nuclei by controlling the dynamics of the gas phase, enabling silicon carbide to grow in the form of nanowires along a specific direction. These nanowires are randomly stacked on the surface of alumina fibers to form an irregularly connected three-dimensional network of nanowire soft interfaces.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] Compared to the typical interface existing on the surface of alumina fibers in ceramic form, the three-dimensional network nanowire soft interface grown on the surface of alumina fibers using the preparation method provided in this invention significantly increases the interfacial surface area of ​​the fiber-matrix interface due to the presence of nanowires. When an external load is applied to the oxide ceramic matrix composite material prepared from this fiber, the shear stress on the nanowire surface, which is widely distributed at the fiber-matrix interface, can increase the energy dissipated during composite material failure, thereby further improving the toughening effect. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0024] Figure 1 This is a flowchart illustrating the preparation process of the three-dimensional network nanowire soft interface on the surface of alumina fibers according to the present invention.

[0025] Figure 2 This is a schematic diagram of a semi-clamp structure;

[0026] Figure 3 This is a schematic diagram of a double-clamp structure;

[0027] Figure 4 This is a schematic diagram of the gas phase entering the dual clamps.

[0028] Figure 5 This is a thickness calibration diagram of the three-dimensional network nanowire soft interface in the alumina fiber with a three-dimensional network nanowire soft interface grown on the surface prepared in Example 1.

[0029] Figure 6 The images are scanning electron microscope (SEM) images of the alumina fibers with a three-dimensional network nanowire soft interface grown on the surface prepared in Example 1 at different magnifications.

[0030] Figure 7 The scanning electron microscope energy dispersive spectroscopy (SEM) image of the alumina fibers with a three-dimensional network nanowire soft interface grown on the surface prepared in Example 1.

[0031] Figure 8 Stress-strain curves of Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material (a) and Al2O3 / SiC interface / Al2O3 composite material (b). Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0036] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0037] This invention provides a method for preparing a three-dimensional network nanowire soft interface on the surface of alumina fibers (see the flowchart). Figure 1 The process includes the following steps:

[0038] After pretreatment, the alumina fibers are fixed with a clamp and placed in a chemical vapor deposition furnace. The furnace is evacuated and heated. After the heating is completed, the temperature is maintained and trichloromethylsilane, hydrogen and argon are introduced for chemical vapor deposition. After deposition, the alumina fibers are cooled to room temperature to obtain alumina fibers with a three-dimensional network of nanowire soft interfaces on the surface.

[0039] In a preferred embodiment of the present invention, the alumina fiber includes one or more of unidirectional alumina fiber, multidirectional alumina fiber, and fiber cloth woven from alumina fiber.

[0040] In a preferred embodiment of the present invention, the alumina fiber pretreatment involves high-temperature sintering of the alumina fibers to remove organic adhesives from the fiber surface. The high-temperature sintering heating rate is 400–600°C / h, the sintering temperature is 500–600°C, and the holding time is 1–3h.

[0041] In a preferred embodiment of the present invention, the chemical vapor deposition furnace is evacuated to a vacuum level of 1-3 kPa, and the temperature is raised to 1000-1300°C at a heating rate of 400-600°C / h.

[0042] In a preferred embodiment of the present invention, during the heating process, argon gas with a flow rate of 100-500 mL / min is introduced to form a protective atmosphere.

[0043] In a preferred embodiment of the present invention, the heat preservation time is 3 to 6 hours.

[0044] In a preferred embodiment of the present invention, during the heat preservation process, the flow rate of trichloromethylsilane is 0.1-0.4 g / min, the flow rate of hydrogen is 1000-3000 mL / min, and the flow rate of argon is 500-1000 mL / min.

[0045] In a preferred embodiment of the present invention, after deposition is completed, the introduction of trichloromethylsilane and hydrogen is stopped, and the flow rate of argon is reduced to 100-500 mL / min.

[0046] In a preferred embodiment of the present invention, the clamp is a graphite clamp, the middle surface of which is provided with circular air holes with a diameter of 3-5 mm, the distance between each air hole being 7-10 mm, and the clamp length being 12-18 cm. A schematic diagram of the clamp structure is shown below. Figure 2 and Figure 3 ,in Figure 2 It is a semi-clamp. Figure 3 For a dual-clamp setup, taking the dual-clamp setup as an example, a schematic diagram of the gas phase entering the clamp is shown below. Figure 4 .

[0047] This invention also provides an alumina fiber with a three-dimensional network nanowire soft interface on its surface prepared by the above preparation method. The nanowires in the three-dimensional network nanowire soft interface on the surface of the alumina fiber have one or more structures such as spiral, curved and folded, with a length of 2 to 30 μm and a thickness of 0.5 to 10 μm.

[0048] The alumina fiber used in the embodiments of the present invention is alumina fiber (Molon-857-0.5K oxidation furnace fiber), which was purchased from Guozhuang New Material Technology Co., Ltd.

[0049] In this embodiment of the invention, room temperature refers to "25±3℃".

[0050] The technical solution of the present invention will be further illustrated by the following embodiments.

[0051] Example 1

[0052] (1) Cut alumina fibers and arrange them in a unidirectional direction, then put them into an oxidation furnace for high-temperature sintering. The heating rate is 500℃ / h, the sintering temperature is 600℃, the heating time is 72min, and then keep them at the temperature for 3h to remove the organic glue remaining on the surface of the fibers during the preparation process.

[0053] (2) Place the alumina fiber obtained in step (1) between two polished graphite jigs (i.e., Figure 3 The double clamp shown is used, and molybdenum wire is used to bind the clamps to prevent the two clamps from slipping.

[0054] (3) Place the fixture containing alumina fiber into the chemical vapor deposition furnace, evacuate the furnace and maintain the vacuum degree at 2 kPa, and raise the temperature to 1200℃ at a rate of 400℃ / h. During the heating process, keep the flow rate of argon gas at 300 mL / min to form a protective atmosphere.

[0055] (4) After the heating is finished, the heat preservation is started. The flow rate of argon is increased to 800 mL / min. At the same time, trichloromethylsilane and hydrogen are continuously introduced at flow rates of 0.4 g / min and 3000 m / min, respectively. The heat preservation time is set to 6 h. During the deposition process, the gas phase (trichloromethylsilane and hydrogen) accumulates on the surface of alumina fiber through the fixture and undergoes a chemical reaction to generate nanowires. The nanowires bend, grow and accumulate, intertwining with each other in multiple dimensions and connecting irregularly, eventually forming a three-dimensional network nanowire soft interface.

[0056] (5) After deposition, stop the flow of trichloromethylsilane and hydrogen, and reduce the flow rate of argon to 300 mL / min to form a protective atmosphere. After the furnace body cools to room temperature, remove the fixture from the furnace body to obtain alumina fibers with a three-dimensional network nanowire soft interface on the surface.

[0057] Figure 5 The thickness calibration diagram of the soft interface of the three-dimensional network nanowires shows that the thickness of the soft interface of the three-dimensional network nanowires is 0.5 to 1 μm.

[0058] The scanning electron microscope (SEM) images of the alumina fibers with a three-dimensional network nanowire soft interface grown on the surface prepared in Example 1 at different magnifications are shown below. Figure 6 ,Depend on Figure 6 It can be seen that the nanowires grown on the surface of alumina fibers are three-dimensional networks with spiral, curved, or folded structures, and a length of 2–30 μm.

[0059] The scanning electron microscope (SEM) energy dispersive spectroscopy (EDS) image of the alumina fibers with a three-dimensional network nanowire soft interface prepared in Example 1 is shown below. Figure 7 ,Depend on Figure 7It can be seen that the fiber contains four elements: aluminum, silicon, carbon, and oxygen, which is consistent with the experimental results of depositing silicon carbide on the surface of alumina fiber.

[0060] Comparative Example 1

[0061] Same as Example 1, except that the use of the fixture is omitted, specifically:

[0062] (1) Cut alumina fibers and arrange them in a unidirectional direction, then put them into an oxidation furnace for high-temperature sintering. The heating rate is 500℃ / h, the sintering temperature is 600℃, the heating time is 72min, and then keep them at the temperature for 3h to remove the organic glue remaining on the surface of the fibers during the preparation process.

[0063] (2) The unidirectional alumina fiber is directly placed into the chemical vapor deposition furnace. The furnace is evacuated and the vacuum degree is maintained at 2 kPa. At the same time, the temperature is raised to 1200℃ at a rate of 400℃ / h. During the heating process, argon gas is introduced at a flow rate of 300 mL / min to form a protective atmosphere.

[0064] (4) After the heating is finished, start the heat preservation. Increase the flow rate of argon to 800 mL / min, and at the same time start to continuously introduce trichloromethylsilane and hydrogen at flow rates of 0.4 g / min and 3000 m / min, respectively. Set the heat preservation time to 6 h.

[0065] (5) After deposition, stop the flow of trichloromethylsilane and hydrogen, and reduce the flow rate of argon to 300 mL / min to form a protective atmosphere. After the furnace body cools to room temperature, remove the fixture from the furnace body to obtain modified alumina fibers.

[0066] Application Example 1

[0067] The alumina fibers with a three-dimensional network nanowire soft interface grown on the surface obtained in Example 1 were used to prepare an Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material. The preparation method is as follows:

[0068] The alumina fibers with a three-dimensional network nanowire soft interface obtained in Example 1 were immersed in alumina sol and placed in a vacuum chamber for vacuum impregnation at a vacuum degree of 0.1 MPa for 7 hours. After impregnation, the alumina fibers containing the three-dimensional network nanowire soft interface were removed from the alumina sol and placed in a drying oven for drying at a temperature of 60-120°C for 10 hours. The impregnation and drying steps were repeated until the final drying was compared with the previous one. The mass increase percentage after the second evaporation was less than 5%, so the cycle was stopped to obtain an Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material green body. The green body was then placed in a muffle furnace for high-temperature sintering. The temperature was increased from room temperature to 800℃ at a rate of 10℃ / min and held for 2 hours. The temperature was then increased from 800℃ to 1000℃ at a rate of 6℃ / min and held for 2 hours to obtain the Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material.

[0069] The modified alumina fibers obtained in Comparative Example 1 were used to prepare an Al2O3 / SiC interface / Al2O3 composite material. The preparation method was the same as that for the Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material, except that the alumina fibers with a three-dimensional network nanowire soft interface grown on the surface obtained in Example 1 were replaced with the modified alumina fibers obtained in Comparative Example 1.

[0070] The Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material was subjected to three-point bending performance testing, repeated 5 times. The stress-strain curves are shown below. Figure 8 (a) The data results are shown in Table 1. The three-point bending performance test of the Al2O3 / SiC interface / Al2O3 composite material was repeated 5 times, and the stress-strain curves are shown in Table 1. Figure 8 (b) The data results are shown in Table 2.

[0071] Table 1. Test results of three-point bending performance of Al2O3 / SiC three-dimensional mesh nanowire soft interface / Al2O3 composite material.

[0072]

[0073] Table 2. Results of three-point bending performance tests on Al2O3 / SiC interface / Al2O3 composite materials.

[0074]

[0075] Combination Figure 7 As can be seen from the data results in Table 1-2, the three-dimensional mesh nanowire soft interface prepared by the preparation method provided by the present invention can further improve the toughening effect.

[0076] Example 2

[0077] (1) Cut alumina fibers and arrange them in a unidirectional direction, then put them into an oxidation furnace for high-temperature sintering. The heating rate is 600℃ / h, the sintering temperature is 600℃, the heating time is 60min, and then keep them at the temperature for 2h to remove the organic glue remaining on the surface of the fibers during the preparation process.

[0078] (2) Place the alumina fiber obtained in step (1) between two graphite jigs with polished surfaces, and use molybdenum wire to bind the jigs to prevent the two jigs from sliding.

[0079] (3) Place the fixture containing alumina fiber into the chemical vapor deposition furnace, evacuate the furnace and maintain the vacuum degree at 1 kPa, and raise the temperature to 1300℃ at a rate of 400℃ / h. During the heating process, keep the flow rate of argon gas at 100 mL / min to form a protective atmosphere.

[0080] (4) After the heating is finished, the heat preservation is started. The flow rate of argon is increased to 500 mL / min. At the same time, trichloromethylsilane and hydrogen are continuously introduced at flow rates of 0.3 g / min and 500 m / min, respectively. The heat preservation time is set to 5 h. During the deposition process, the gas phase (trichloromethylsilane and hydrogen) accumulates on the surface of alumina fiber through the fixture and undergoes a chemical reaction to generate nanowires. The nanowires bend, grow and accumulate, intertwining with each other in multiple dimensions and connecting irregularly, eventually forming a three-dimensional network nanowire soft interface.

[0081] (5) After deposition, stop the flow of trichloromethylsilane and hydrogen, and reduce the flow rate of argon to 500 mL / min to form a protective atmosphere. After the furnace body cools to room temperature, remove the fixture from the furnace body to obtain alumina fibers with a three-dimensional network nanowire soft interface on the surface.

[0082] Comparative Example 2

[0083] Same as Example 2, except that the use of the clamp is omitted.

[0084] Application Example 2

[0085] The alumina fibers with a three-dimensional network nanowire soft interface grown on the surface obtained in Example 2 were used to prepare an Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material, and the preparation method was the same as in Application Example 1.

[0086] The modified alumina fibers obtained in Comparative Example 2 were used to prepare an Al2O3 / SiC interface / Al2O3 composite material. The preparation method was the same as that for the Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material, except that the alumina fibers with a three-dimensional network nanowire soft interface grown on the surface obtained in Example 2 were replaced with the modified alumina fibers obtained in Comparative Example 2.

[0087] Three-point bending performance tests were conducted on Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material and Al2O3 / SiC interface / Al2O3 composite material, repeated 5 times. The performance test data are shown in Tables 3 and 4.

[0088] Table 3. Test results of three-point bending performance of Al2O3 / SiC three-dimensional mesh nanowire soft interface / Al2O3 composite material.

[0089]

[0090] Table 4. Results of Three-Point Bending Performance Measurement of Al2O3 / SiC Interface / Al2O3 Composite Material

[0091]

[0092] The data results in Tables 3 and 4 show that the three-dimensional mesh nanowire soft interface prepared by the preparation method provided by this invention can further improve the toughening effect.

[0093] Example 3

[0094] (1) Cut alumina fibers and arrange them in a unidirectional direction, then put them into an oxidation furnace for high-temperature sintering. The heating rate is 400℃ / h, the sintering temperature is 500℃, the heating time is 75min, and then keep them at the temperature for 1h to remove the organic glue remaining on the surface of the fibers during the preparation process.

[0095] (2) Place the alumina fiber obtained in step (1) between two graphite jigs with polished surfaces, and use molybdenum wire to bind the jigs to prevent the two jigs from sliding.

[0096] (3) Place the fixture containing alumina fiber into the chemical vapor deposition furnace, evacuate the furnace, maintain the vacuum degree at 3 kPa, and raise the temperature to 1000℃ at a rate of 600℃ / h. During the heating process, keep the flow rate of argon gas at 500 mL / min to form a protective atmosphere.

[0097] (4) After the heating is finished, the heat preservation is started. The flow rate of argon gas is increased to 1000 mL / min. At the same time, trichloromethylsilane and hydrogen are continuously introduced at flow rates of 0.1 g / min and 1000 m / min, respectively. The heat preservation time is set to 4 h. During the deposition process, the gas phase (trichloromethylsilane and hydrogen) accumulates on the surface of alumina fiber through the fixture, and a chemical reaction occurs to generate nanowires. The nanowires bend, grow and accumulate, intertwine with each other in multiple dimensions and connect irregularly, and finally form a three-dimensional network nanowire soft interface.

[0098] (5) After deposition, stop the flow of trichloromethylsilane and hydrogen, and reduce the flow rate of argon to 100 mL / min to form a protective atmosphere. After the furnace body cools to room temperature, remove the fixture from the furnace body to obtain alumina fibers with a three-dimensional network nanowire soft interface on the surface.

[0099] Comparative Example 3

[0100] Same as Example 3, except that the use of the clamp is omitted.

[0101] Application Example 3

[0102] The alumina fibers with a three-dimensional network nanowire soft interface grown on the surface obtained in Example 3 were used to prepare an Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material, and the preparation method was the same as in Application Example 1.

[0103] The modified alumina fibers obtained in Comparative Example 3 were used to prepare an Al2O3 / SiC interface / Al2O3 composite material. The preparation method was the same as that for the Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material, except that the alumina fibers with a three-dimensional network nanowire soft interface grown on the surface obtained in Example 3 were replaced with the modified alumina fibers obtained in Comparative Example 3.

[0104] Three-point bending performance tests were conducted on Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material and Al2O3 / SiC interface / Al2O3 composite material, repeated 5 times. The performance test data are shown in Tables 5 and 6.

[0105] Table 5. Test results of three-point bending performance of Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material.

[0106]

[0107] Table 6. Results of Three-Point Bending Performance Measurements of Al2O3 / SiC Interface / Al2O3 Composite Material

[0108]

[0109]

[0110] The data results in Tables 5 and 6 show that the three-dimensional mesh nanowire soft interface prepared by the preparation method provided by the present invention can further improve the toughening effect.

[0111] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. The application of alumina fibers with a three-dimensional network of nanowire soft interfaces on their surface in the preparation of alumina fiber-reinforced oxide ceramic matrix composites, characterized in that, The preparation method of the alumina fiber reinforced oxide ceramic matrix composite material includes the following steps: Alumina fibers with a three-dimensional network nanowire soft interface grown on their surface were immersed in alumina sol and then placed in a vacuum chamber for vacuum impregnation at a vacuum degree of 0.1 MPa for 7 hours. After impregnation, the fibers were removed and placed in a drying oven for drying at a temperature of 60-120°C for 10 hours. The impregnation and drying steps were repeated until the mass increase after the last drying was less than 5% compared to the previous drying. The cycle was then stopped to obtain an Al2O3 / SiC three-dimensional network nanowire soft interface / Al2O3 composite material green body. The green body was then placed in a muffle furnace for high-temperature sintering. The temperature was increased from room temperature to 800°C at a rate of 10°C / min and held for 2 hours. The temperature was then increased from 800°C to 1000°C at a rate of 6°C / min and held for 2 hours to obtain the alumina fiber reinforced oxide ceramic matrix composite material. The method for preparing the alumina fiber with a three-dimensional network of nanowire soft interfaces on its surface includes the following steps: After pretreatment, the alumina fibers are fixed with a clamp and placed in a chemical vapor deposition furnace. The furnace is evacuated and heated. After the heating is completed, the temperature is maintained and trichloromethylsilane, hydrogen and argon are introduced for chemical vapor deposition. After deposition, the temperature is cooled to room temperature to obtain alumina fibers with a three-dimensional network nanowire soft interface on the surface. The alumina fiber pretreatment involves high-temperature sintering of the alumina fiber, wherein the high-temperature sintering heating rate is 400-600℃ / h, the sintering temperature is 500-600℃, and the holding time is 1-3h. The chemical vapor deposition furnace is evacuated to a vacuum level of 1-3 kPa, and the temperature is raised to 1000-1300℃ at a heating rate of 400-600℃ / h. The clamp has circular air holes with a diameter of 3-5 mm on the middle surface, the distance between each air hole is 7-10 mm, and the clamp length is 12-18 cm.

2. The application of alumina fibers with a three-dimensional network nanowire soft interface on their surface according to claim 1 in the preparation of alumina fiber-reinforced oxide ceramic matrix composites, characterized in that, In the preparation method of the alumina fiber with a three-dimensional network nanowire soft interface on the surface, argon gas with a flow rate of 100-500 mL / min is introduced during the heating process to form a protective atmosphere.

3. The application of alumina fibers with a three-dimensional network nanowire soft interface on their surface according to claim 1 in the preparation of alumina fiber-reinforced oxide ceramic matrix composites, characterized in that, In the preparation method of the alumina fiber with a three-dimensional network nanowire soft interface on the surface, the chemical vapor deposition furnace is evacuated and heated, and the holding time after the heating is completed is 3 to 6 hours.

4. The application of alumina fibers with a three-dimensional network nanowire soft interface on their surface according to claim 1 in the preparation of alumina fiber-reinforced oxide ceramic matrix composites, characterized in that, In the preparation method of the alumina fiber with a three-dimensional network nanowire soft interface on the surface, the chemical vapor deposition furnace is evacuated and heated. After the heating is completed, the furnace is kept at a constant temperature. During the holding process, the flow rate of trichloromethylsilane is 0.1-0.4 g / min, the flow rate of hydrogen is 1000-3000 mL / min, and the flow rate of argon is 500-1000 mL / min.

5. The application of alumina fibers with a three-dimensional network nanowire soft interface on their surface according to claim 1 in the preparation of alumina fiber-reinforced oxide ceramic matrix composites, characterized in that, In the preparation method of alumina fibers with a three-dimensional network nanowire soft interface on the surface, after deposition is completed, the introduction of trichloromethylsilane and hydrogen is stopped, and the flow rate of argon is reduced to 100-500 mL / min.

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