Process for the preparation of a stealth structured oxide fibre reinforced silicon based ceramic composite material

Abstract

The application provides a preparation method of an invisible structure type oxide fiber reinforced silicon-based ceramic composite material, and the method comprises the following steps: laminating plain weave aluminum oxide fiber cloth to form an aluminum oxide fiber preform; preparing a BN and PyC composite interface in the prepared aluminum oxide fiber preform through a chemical vapor infiltration process; preparing a SiOC matrix through a polymer impregnation and pyrolysis process for the obtained material containing the BN and PyC composite interface, so as to obtain a porous Al2O 3f / SiOC composite material; oxidizing the obtained porous Al2O 3f / SiOC composite material in an air environment at 500-600 DEG C for 10-40 h; filling the obtained Al2O 3f / SiOC composite material through the chemical vapor infiltration process to obtain an Al2O 3f / Si3N4 composite material. The application introduces a low-interfacial BN interface and a high-conductivity PyC interface into the composite material, successfully prepares a BN-C interface by regulating the interface thickness, interface state and interface component, and further optimizes the mechanical / absorbing performance of the Al2O 3f -CMC, so as to obtain an invisible structure type ceramic matrix composite material.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of microwave absorbing structural ceramic matrix composite technology, and more specifically, to a method for preparing a stealth structural oxide fiber reinforced silicon-based ceramic composite material. Background Technology

[0002] High-temperature load-bearing, wave-absorbing ceramic matrix composites will become key materials for the high-temperature tail nozzle components of next-generation stealth fighters, possessing broad application prospects and significant strategic importance. Currently, the high-temperature load-bearing, wave-absorbing ceramic matrix composites under in-depth research mainly focus on silicon carbide fiber-reinforced ceramic matrix composites (SiC). f -CMC) and alumina fiber-reinforced ceramic matrix composites (Al2O 3f -CMC). Since the electrical conductivity of SiC fibers is closely related to their composition and microstructure, obtaining wave-absorbing SiC fibers requires... f CMC requires comprehensive design and optimization of the structural and electrical properties of each component in the composite material, which is very challenging. Al2O 3f In CMC (Ceramic Matrix Composites), both the fiber and the matrix are low-dielectric-loss materials with excellent impedance matching characteristics. The microwave absorption performance of the composite material can be optimized simply by introducing an absorbing phase between the fiber and the matrix (i.e., the interface). In ceramic matrix composites, the interface is not only a key component for controlling mechanical properties, but it can also impart microwave absorption properties by adding a conductive phase, enabling the composite material to possess both load-bearing and microwave-absorbing properties. BN (Bio-Nearest Neural Network) and PyC (PyC) are commonly used interfaces in ceramic matrix composites. The BN interface is a low-dielectric-loss material, while the PyC interface is a highly conductive material. By combining the BN and PyC interfaces, an absorbing interface that meets the mechanical performance requirements of ceramic matrix composites can be obtained. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing the microwave absorbing interface of a stealth-structured oxide fiber reinforced silicon-based ceramic composite material, so as to solve the problems of difficulty in optimizing the microwave absorbing performance of ceramic matrix composite materials and difficulty in synergizing mechanical and microwave absorbing performance.

[0004] To achieve the above objectives, the present invention provides a method for preparing a microwave absorbing interface of a stealth-structured alumina fiber-reinforced ceramic matrix composite material. The reinforcing phase of the composite material is alumina fiber, the interface phase is a CVI (chemical vapor infiltration) BN and PyC multiphase interface (referred to as BN-C interface), and the matrix is ​​a SiOC-Si3N4 matrix prepared by polymer impregnation pyrolysis (PIP) combined with CVI process.

[0005] According to the present invention, the preparation method of the stealth structure type oxide fiber reinforced silicon-based ceramic composite material includes the following steps:

[0006] Step 1: Lay the plain-weave alumina fiber cloth in layers to form an alumina fiber preform;

[0007] Step 2: Prepare a BN and PyC composite interface in the alumina fiber preform prepared in Step 1 using a chemical vapor infiltration process;

[0008] Step 3: The material containing the BN and PyC composite interface obtained in Step 2 is used to prepare a SiOC matrix through a polymer impregnation pyrolysis process to obtain porous Al2O. 3f / SiOC composite materials;

[0009] Step 4: The porous Al2O2 obtained in Step 3... 3f / SiOC composite material is oxidized in air at 500-600℃ for 10-40 hours;

[0010] Step 5: Fill the Al2O2 obtained from oxidation in Step 4 with the chemical vapor infiltration process. 3f / SiOC composite material porosity yields Al2O 3f / SiOC-Si3N4 composite material.

[0011] As a further explanation of the present invention, the alumina fiber cloth in step 1 is 18-22 layers of alumina fiber cloth, and the shaping of the alumina fiber preform uses SiO2 fiber; and the alumina fiber cloth needs to be cut to a certain size before being laminated.

[0012] As a further explanation of the present invention, the composite order of the BN and PyC composite interface is to prepare the BN interface first, followed by the PyC interface.

[0013] As a further explanation of the present invention, the thickness of the BN and PyC composite interface is 200-400 nm.

[0014] As a further explanation of the present invention, the porous Al2O in step 3 3f The SiOC composite material has an open porosity of >20% and a density of 2.6 g / cm³. 3 .

[0015] As a further explanation of the present invention, the interface thickness after air oxidation treatment in step 4 is 100-300 nm.

[0016] As a further illustration of the present invention, the Al2O obtained in step 5 3f The SiOC-Si3N4 composite material has an open porosity of <10% and a density of 2.75 g / cm³. 3 .

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0018] 1. This invention utilizes high-performance Al2O with low dielectric loss. 3f Using CMC as the research object, a low-dielectric-loss BN interface and a high-conductivity PyC interface were introduced into the composite material. By controlling the interface thickness, interface state, and interface composition, a BN-C interface was successfully prepared, thereby synergistically optimizing Al2O3. 3f - The mechanical / wave-absorbing properties of CMC enable the acquisition of stealth structural ceramic matrix composites.

[0019] 2. This invention utilizes low-temperature oxidation of porous Al2O2. 3f -CMC is used to optimize the mechanical and microwave absorption properties of composite materials, resulting in a stealthy Al2O structure. 3f -CMC can absorb more than 90% of electromagnetic waves in the X-band while maintaining good mechanical properties.

[0020] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. It should be understood that the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention, wherein:

[0022] Figure 1 A photograph showing the molding of an alumina fiber preform.

[0023] Figure 2 This is a schematic diagram of the microwave absorption performance of the alumina fiber reinforced ceramic matrix composite material prepared in Example 1 of the present invention, wherein a is the RC curve of different thicknesses as a function of frequency, and b is the graph of reflection loss as a function of thickness and frequency.

[0024] Figure 3 This is a schematic diagram of the microwave absorption performance of the alumina fiber reinforced ceramic matrix composite material prepared in Example 3 of the present invention, wherein a is the RC curve of different thicknesses as a function of frequency, and b is the graph of reflection loss as a function of thickness and frequency.

[0025] Figure 4 The images show the microstructure of the alumina fiber-reinforced ceramic matrix composite material obtained in Example 3 of this invention, where a is a low-magnification microstructure image and b is a high-magnification interface morphology image.

[0026] Figure 5The images show the fracture morphology of the alumina fiber-reinforced ceramic matrix composite material obtained in Example 3 of the present invention, where a is a low-magnification fracture morphology image and b is a fiber debonding and pull-out morphology image. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0028] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. Example 1

[0029] This embodiment provides a method for preparing a stealth-structured oxide fiber reinforced silicon-based ceramic composite material, including the following steps:

[0030] (1) Preparation of fiber preform: The plain weave Al2O3 fiber cloth is cut into 150mm*250mm size, layered according to the required material thickness, and fixed by graphite mold to shape SiO2 fiber.

[0031] (2) Interface preparation: In the alumina fiber preform prepared in step 1, a PyC interface with a thickness of 100 nm and a BN interface with a thickness of 200 nm are prepared by CVI process.

[0032] (3) PIP matrix preparation: A precursor solution was prepared by mixing polysiloxane and xylene at a mass ratio of 1:1. The material prepared in step (2) was vacuum impregnated in this precursor solution for 1 hour. After removal, it was cured in an oven at 200°C for 2 hours. Then, under a N2 atmosphere, the temperature was increased to 800°C at 5°C / min and held for 2 hours. After that, the temperature was decreased to 600°C at 5°C / min and cooled to room temperature in the oven. This process was repeated four times to obtain porous Al2O3. 3f The SiOC composite material has an open porosity >20% and a density of approximately 2.6 g / cm³. 3 .

[0033] (4) Oxidation treatment: to treat porous Al2O 3f The / SiOC composite material was oxidized at 550℃ for 30 hours.

[0034] (5) Densification treatment: The composite material CVI Si3N4 obtained in step (4) is densified. substrate Repeat five times to obtain Al2O 3f The open porosity of the / SiOC-Si3N4 composite material is <10%, and its density is approximately 2.75 g / cm³. 3 . Example 2

[0035] This embodiment provides a method for preparing a stealth-structured oxide fiber reinforced silicon-based ceramic composite material, including the following steps:

[0036] (1) Preparation of fiber preform: The plain weave Al2O3 fiber cloth is cut into 150mm*250mm size, layered according to the required material thickness, and fixed by graphite mold to shape SiO2 fiber.

[0037] (2) Interface preparation: In the alumina fiber preform prepared in step 1, a BN interface with a thickness of 100 nm, a PyC interface with a thickness of 100 nm and a BN interface with a thickness of 100 nm are prepared by CVI process.

[0038] (3) PIP matrix preparation: A precursor solution was prepared by mixing polysiloxane and xylene at a mass ratio of 1:1. The material prepared in step (2) was vacuum impregnated in this precursor solution for 1 hour. After removal, it was cured in an oven at 200°C for 2 hours. Then, under a N2 atmosphere, the temperature was increased to 800°C at 5°C / min and held for 2 hours. After that, the temperature was decreased to 600°C at 5°C / min and cooled to room temperature in the oven. This process was repeated four times to obtain porous Al2O3. 3f The SiOC composite material has an open porosity >20% and a density of approximately 2.6 g / cm³. 3 .

[0039] (4) Oxidation treatment: to treat porous Al2O 3f The / SiOC composite material was oxidized at 550℃ for 20 hours.

[0040] (5) Densification treatment: The composite material CVI Si3N4 obtained in step (4) is densified. substrate Repeat five times to obtain Al2O 3f The open porosity of the / SiOC-Si3N4 composite material is <10%, and its density is approximately 2.75 g / cm³. 3 . Example 3

[0041] This embodiment provides a method for preparing a stealth-structured oxide fiber reinforced silicon-based ceramic composite material, including the following steps:

[0042] (1) Preparation of fiber preform: The plain weave Al2O3 fiber cloth is cut into 150mm*250mm size, layered according to the required material thickness, and fixed by graphite mold to shape SiO2 fiber.

[0043] (2) Interface preparation: A BN interface with a thickness of 200 nm and a PyC interface with a thickness of 100 nm are prepared in the alumina fiber preform prepared in step 1 using the CVI process.

[0044] (3) PIP matrix preparation: A precursor solution was prepared by mixing polysiloxane and xylene at a mass ratio of 1:1. The material prepared in step (2) was vacuum impregnated in this precursor solution for 1 hour. After removal, it was cured in an oven at 200°C for 2 hours. Then, under a N2 atmosphere, the temperature was increased to 800°C at 5°C / min and held for 2 hours. After that, the temperature was decreased to 600°C at 5°C / min and cooled to room temperature in the oven. This process was repeated four times to obtain porous Al2O3. 3f The SiOC composite material has an open porosity >20% and a density of approximately 2.6 g / cm³. 3 .

[0045] (4) Oxidation treatment: to treat porous Al2O 3f The / SiOC composite material was oxidized at 550℃ for 15 hours.

[0046] (5) Densification treatment: The composite material obtained in step (4) is further densified by CVI Si3N4 substrate Repeat five times to obtain Al2O 3f The open porosity of the / SiOC-Si3N4 composite material is <10%, and its density is approximately 2.75 g / cm³. 3 .

[0047] The composite material prepared in Example 1 has a real part of dielectric constant of 11.84 and an imaginary part of 19.16 in the X-band, achieving full-frequency absorption of <-4dB in the X-band. RC min =-4.56dB. Mechanical property tests were performed on the composite material of Example 1, and its flexural strength was 313.74MPa, and its fracture toughness was 6.59MPa·m. 1 / 2 The composite material prepared in Example 3 has a real part of dielectric constant of 6.67 and an imaginary part of 5.13 in the X-band, achieving full-frequency absorption of <-10dB in the X-band. RC min =-17.83dB. Mechanical property tests were performed on the composite material of this embodiment; its flexural strength was 314.44MPa, and its fracture toughness was 10.64MPa·m. 1 / 2 .

[0048] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for producing a stealth structural oxide fiber-reinforced silicon-based ceramic composite material, characterized by, The method comprises the following steps: Step 1: laminating plain-woven alumina fiber cloth to form an alumina fiber preform; Step 2: preparing a BN and PyC composite interface in the alumina fiber preform prepared in step 1 by a chemical vapor infiltration process, wherein the composite sequence of the BN and PyC composite interface is to prepare the BN interface first and then prepare the PyC interface; and the thickness of the BN and PyC composite interface is 200-400 nm; Step 3: The material comprising the BN and PyC composite interface from Step 2 is prepared with a SiOC matrix by a polymer impregnation pyrolysis process to produce a porous Al2O 3f / SiOC composite; Step 4: The porous Al2O3 / SiOC composite obtained in Step 3 was oxidized in air at 500-600°C for 10-40h. 3f / SiOC composite was oxidized in air at 500-600°C for 10-40h. Step 5: Fill the Al2O2 obtained from oxidation in Step 4 using a chemical vapor infiltration process. 3f / SiOC composite material porosity yields Al2O 3f / SiOC-Si3N4 composite material.

2. The method of claim 1, wherein, In step 1, the alumina fiber cloth is 18-22 layers of alumina fiber cloth, the alumina fiber preform is shaped using SiO2 fiber; and the alumina fiber cloth needs to be cut into a certain size before being laminated.

3. The method of claim 1, wherein, The porous Al2O3 3f / SiOC composite has a porosity of >20% and a density of 2.6 g / cm 3 .

4. The method of claim 1, wherein, In step 4, the interface thickness after the air oxidation treatment is 100-300 nm.

5. The method of claim 1, wherein, Al2O3 obtained in step 5 3f The open porosity of the / SiOC-Si3N4 composite material is <10% and the density is 2.75 g / cm 3 .

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