Preparation method of lossless large-size curved cyanate ester quartz functional composite material

Abstract

The application discloses a preparation method of a lossless large-size curved cyanate ester quartz functional composite material. Four fluorine cloth layers, first porous isolation film layers, equalizing plates, second porous isolation film layers, air-permeable felt and vacuum bag films are sequentially laid on the outer surface of a functional composite material layer. The area of the fluorine cloth can cover the functional composite material layer and unvulcanized rubber strips. The edges of the equalizing plates are flush with the fluorine cloth. The edges of the first and second porous isolation film layers exceed the fluorine cloth by 20-30 mm. The edges of the air-permeable felt exceed the second porous isolation film layer by 10-20 mm. After packaging, a metal male die is placed in a hot press tank. Under high temperature and high pressure, the functional composite material layer is exhausted and solidified to obtain a lossless large-size curved cyanate ester quartz prepreg composite material. The application ensures that the air path of the cyanate ester quartz prepreg is smooth under high temperature and high pressure, facilitates overflow of the cyanate ester resin, and ensures that the wrapped air is discharged and volatile components in the solidification process are discharged.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic communication technology, specifically relating to a method for preparing non-destructive large-size curved cyanate quartz functional composite materials. Background Technology

[0002] Resin-based functional composites are co-cured, conformal electromagnetic functional structural components composed of composite materials, functional layers (such as shielding copper mesh, FSS, resistive films, and other metamaterials), and films. They are characterized by component diversity and designability, possessing not only excellent mechanical properties but also advanced electromagnetic characteristics, making them widely used in electromagnetic windows of spacecraft. Commonly used composite materials include quartz cyanate prepreg and cyanate films. Quartz cyanate prepreg, with its dielectric constant of approximately 3.3 and loss tangent of approximately 0.0065, exhibits excellent dielectric properties, making it an ideal material for preparing resin-based functional composites.

[0003] Cyanate ester quartz prepreg has a high Tg temperature, about 210℃, and its curing temperature is also high, generally 180℃. To achieve the conformal structure of the composite material and functional layer, the conventional process is the autoclave process. The layers are laid on the surface of the metal mold, and then PTFE cloth, non-porous release film, pressure equalization plate, breathable felt and vacuum bag film are sequentially laid on the surface for sealing. The autoclave is used to provide high temperature and high pressure for curing.

[0004] However, when preparing large-sized conformal functional composite parts containing composite materials, functional layers, and adhesive films, snowflake patterns frequently appear on the surface of the composite parts, and internal non-destructive A-scan inspection reveals diffuse defects, failing to meet the non-destructive quality requirements of aircraft. Analysis revealed that this is due to the poor adhesion of the cyanate quartz prepreg layer during the layering process, making it difficult to lay and prone to air entrapment. Although pre-compaction and hot-compaction processes reduce the laying difficulty and minimize air entrapment, the poor fluidity of the cyanate quartz resin during curing and the generation of volatiles during curing still present challenges. Conventional autoclave processes and pressure equalization plate structures involve layering PTFE cloth, non-porous release film, pressure equalization plate, porous release film, breathable adhesive, and vacuum bag film, failing to consider the low adhesion and poor fluidity of cyanate quartz during curing. This hinders the flow of cyanate quartz resin and the overflow of volatiles, easily leading to pores, voids, and other non-destructive diffuse defects inside the cured part, resulting in substandard non-destructive quality. Therefore, it is necessary to design and optimize the packaging process for large-size curved cyanate quartz prepreg composites. Summary of the Invention

[0005] Purpose of the invention / Technical problemThis invention addresses the technical problems existing in the prior art by proposing a method for preparing non-destructive large-size curved cyanate quartz functional composite materials. The process scheme of this invention can ensure that no non-destructive defects such as pores and voids are generated inside the composite parts, thus significantly improving the non-destructive quality of the composite parts.

[0006] Technical Solution: To achieve the above-mentioned technical objectives, the present invention provides the following technical solution: a method for preparing a non-destructive large-size curved cyanate quartz functional composite material, comprising the following steps: S1, After the functional composite material is laid layer by layer on the surface of the metal male mold in multiple layers, an uncured rubber strip of equal thickness is laid on the outer periphery of the functional composite material layer. S2, a PTFE cloth layer, a first porous isolation membrane layer, a pressure equalizing plate, a second porous isolation membrane layer, and a breathable felt are sequentially laid on the outer surface of the functional composite material layer, wherein: The PTFE cloth has an area sufficient to cover the functional composite material layer and the uncured rubber strip. The edge of the pressure equalizing plate is flush with the PTFE cloth. The edges of the first and second porous isolation membrane layers extend 20-30 mm beyond the PTFE cloth, and the edge of the breathable felt extends 10-20 mm beyond the second porous isolation membrane layer. S3. After setting a sealing strip around the breathable felt, a vacuum bag film is laid on the outermost layer to complete the sealing process. S4. After the metal male mold is encapsulated, it is placed in a hot autoclave. Under high temperature and high pressure, the functional composite material layer is degassed and cured to obtain a large-size curved cyanate quartz prepreg composite part without damage.

[0007] Preferably, the pressure equalizing plate is provided with an array of air guide holes with a diameter not exceeding Φ2mm.

[0008] Preferably, the functional composite material includes cyanate quartz prepreg, a functional layer, and a cyanate film.

[0009] Preferably, when the functional composite material is laid in 3 to 5 layers, a pre-compaction is performed by sequentially laying a PTFE cloth layer, a porous isolation membrane layer, a breathable felt, and a vacuum bag film on the functional composite material layer to expel the trapped air and the prepreg laid in the compacted layer.

[0010] Beneficial effects: Compared with the prior art, the present invention has the following advantages: (1) Firstly, the process solution involved in this invention is more suitable for preparing functional composite material products with large curved surface structures than traditional packaging processes. The process solution has a pre-set overflow channel in the packaging process when preparing large curved cyanate quartz prepreg composite parts, which facilitates the flow of cyanate resin and the overflow of volatiles under high temperature and high pressure. The internal porosity of the parts is low and the parts have high quality without damage.

[0011] (2) The first layer of PTFE cloth is connected to the breathable felt, and the second layer is changed to a porous isolation membrane, which can ensure the breathability of the entire part and prevent the volatiles inside the cyanate resin in the center from being unable to be discharged.

[0012] (3) Φ2mm overflow holes are uniformly prepared on the surface of the pressure equalizing plate. This ensures that the air passage of the entire surface of the part is unobstructed and that no hole marks are left on the surface of the product, making the surface of the part smooth and avoiding affecting the appearance quality.

[0013] (4) Add AIRPAD strips around the perimeter to prevent excessive resin from flowing out from the edges, which would result in thinner product edges and ensure the consistency of overall thickness. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the cross-sectional structure of the non-destructive large-size curved cyanate quartz functional composite material described in this invention after it has been laid.

[0015] Figure 2 yes Figure 1 Top view.

[0016] Figure 3 This is an enlarged cross-sectional view of the non-destructive large-size curved cyanate quartz functional composite material described in this invention during installation.

[0017] In the figure, 1. Metal male mold, 2. Vacuum bag film, 3. Breathable felt, 4. First porous isolation membrane, 5. Functional composite material, 6. Pressure equalizing plate, 7. Second porous isolation membrane, 8. PTFE cloth, 9. Uncured rubber strip, 10. Sealing strip. Detailed Implementation

[0018] 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 embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specifically stated, the relative arrangement, expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0019] The product involved in the process scheme of this invention mainly consists of four parts: metal mold, functional composite material, pressure equalization plate, and packaging auxiliary materials. Among them: Metal molds are generally male or female frame structures, mainly used for the layup and curing of functional composite materials. Functional composite materials generally include cyanate quartz prepreg, functional layers, and cyanate film, mainly used to realize the electromagnetic function of the product and are the object of process improvement. A pressure equalizing plate is a relatively thin composite material skin, generally no more than 1 mm thick, with uniformly prepared overflow holes no more than 2 mm in diameter on its surface, mainly used to improve the surface quality of composite parts and provide overflow channels. Encapsulation auxiliary materials mainly consist of PTFE cloth, porous separator, pressure equalizing plate, breathable felt, uncured rubber strips, vacuum bag film, and sealing strips, mainly used for the curing of functional composite materials. For example... Figure 1 As shown, the specific preparation method of the non-destructive large-size curved cyanate quartz functional composite material of the present invention includes the following steps: S1. The surface of the metal male mold is cleaned and a release agent is applied. The functional composite material is laid layer by layer on the surface of the metal male mold. During the layer laying process, pre-compaction and hot compaction are required to ensure that the prepreg is pre-compacted and to remove trapped air.

[0020] S2, attach a 10mm wide uncured rubber strip around the functional composite material, with a thickness close to that of the functional composite material, close to the functional composite material.

[0021] Apply two rings of sealing tape to the bagging area of ​​the metal male mold.

[0022] S3, then continue with the first layer of PTFE cloth, extending 50-100mm beyond the uncured rubber strip, so as to connect with the breathable felt; The second layer consists of a porous release membrane, not exceeding the size of the unvulcanized rubber strip; The third layer consists of a pressure equalization plate with Φ2mm air vents arranged in a 50-100mm x 50-100mm array on its surface, tailored to the size of the part. The dimensions of the pressure equalization plate must not exceed those of the functional composite material to avoid interference between the edges and the uncured rubber strips. The fourth layer is a porous release membrane, extending 20-30mm beyond the uncured rubber strip; The fifth layer consists of a breathable felt, with the edges in contact with the sealing strip. The sixth layer involves laying a vacuum bag film to complete the entire sealing process.

[0023] S4. After encapsulation, the metal positive mold is placed in a hot autoclave for curing. Under the high temperature and high pressure of the hot autoclave, the viscosity of the cyanate resin begins to decrease, and the fluidity of the resin improves. The volatiles and air inside the cyanate resin will gradually overflow along the small holes on the porous isolation membrane and the Φ2mm air guide holes on the surface of the pressure equalizing plate. At the same time, the uncured rubber strips around the perimeter can block more cyanate resin.

[0024] The specific process requirements of this invention are as follows: The metal mold is pre-cleaned and coated with a release agent. Then, the functional composite material is laid layer by layer onto the surface of the metal mold according to the layup design. When there are many layers, pre-compaction is performed every 3 to 5 layers to expel air trapped during laying and prepreg in the compacted layers. After laying, uncured rubber strips with a thickness close to that of the product are laid around the perimeter of the composite material. Then, the encapsulation auxiliary materials are applied. The first layer, PTFE cloth, must be in contact with the breathable felt on all four sides, extending 50-100mm beyond the uncured rubber strip. The second layer, a non-porous release liner, is replaced with a porous release liner, and its size must not exceed the uncured rubber strip. The third layer, a pressure equalizing plate, must not exceed the four edges of the part, and its surface must have approximately 50-100*50-100mm arrays of Φ2mm overflow holes, with a diameter not exceeding 2mm, prepared according to the part's area. The fourth layer, a porous release liner, must extend 20-30mm beyond the curing rubber strip. The fifth layer, a breathable felt, must be in close contact with the sealing strip to prevent the vacuum bag from directly contacting the metal mold. The sixth layer, a vacuum bag film, must be approximately 1.5 times the product area. This design ensures unobstructed airflow for the cyanate quartz prepreg under high temperature and pressure, facilitating the overflow of cyanate resin and easily expelling air trapped during application and volatiles released during curing.

[0025] The above description is only a partial 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 method for preparing a non-destructive large-size curved cyanate quartz functional composite material, characterized in that, Includes the following steps: S1, After the functional composite material is laid layer by layer on the surface of the metal male mold in multiple layers, an uncured rubber strip of equal thickness is laid on the outer periphery of the functional composite material layer. S2, a PTFE cloth layer, a first porous isolation membrane layer, a pressure equalizing plate, a second porous isolation membrane layer, and a breathable felt are sequentially laid on the outer surface of the functional composite material layer, wherein: The PTFE cloth has an area sufficient to cover the functional composite material layer and the uncured rubber strip. The edge of the pressure equalizing plate is flush with the PTFE cloth. The edges of the first and second porous isolation membrane layers extend 20-30 mm beyond the PTFE cloth, and the edge of the breathable felt extends 10-20 mm beyond the second porous isolation membrane layer. S3. After setting a sealing strip around the breathable felt, a vacuum bag film is laid on the outermost layer to complete the sealing process. S4. After the metal male mold is encapsulated, it is placed in a hot autoclave. Under high temperature and high pressure, the functional composite material layer is degassed and cured to obtain a large-size curved cyanate quartz prepreg composite part without damage.

2. The method for preparing the non-destructive large-size curved cyanate quartz functional composite material according to claim 1, characterized in that, The pressure equalizing plate is uniformly provided with an array of air guide holes no larger than Φ2mm.

3. The method for preparing the non-destructive large-size curved cyanate quartz functional composite material according to claim 1, characterized in that, The functional composite material includes cyanate quartz prepreg, a functional layer, and a cyanate film.

4. The method for preparing the non-destructive large-size curved cyanate quartz functional composite material according to claim 3, characterized in that, When the functional composite material is laid in 3 to 5 layers, a pre-compaction is performed by sequentially laying a PTFE cloth layer, a porous isolation membrane layer, a breathable felt, and a vacuum bag film on the functional composite material layer to expel the trapped air and the prepreg laid in the compacted layer.

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