Integrally-formed fairing and preparation method thereof

Abstract

The invention relates to an integrally formed fairing and a preparation method thereof. The integrally formed fairing is prepared by a method of combining mesophase pitch-based carbon fiber prepreg and quartz fiber prepreg. The mesophase pitch-based carbon fiber prepreg cloth is of a sandwich structure formed by mesophase pitch-based carbon fibers and a resin matrix, the quartz fiber prepreg cloth is of a sandwich structure formed by quartz fiber woven cloth and a resin matrix, and the resin matrix is formed by doping fused quartz ceramic in cyanate ester resin. According to the fairing, the production process that two kinds of fiber prepreg cloth are combined is adopted, and optimization of the material performance is achieved. Compared with the prior art, the fairing has the advantages of being high in strength, excellent in heat conduction performance, light in weight, resistant to high temperature and high in stability under the extreme temperature condition.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft, and in particular relates to an integrally formed fairing and a preparation method thereof. Background Art

[0002] At present, there are two main types of fairings at home and abroad: metal riveted structures and composite materials structures. Commonly used materials are aluminum alloy metal materials and resin-based fiber composite materials with wave-transmitting functions such as glass fiber and carbon fiber.

[0003] Aluminum alloy metal materials are relatively strong, can provide good protection for the covered parts, and have good high temperature resistance and can withstand a certain amount of aerodynamic heating; but they are heavy, which may affect the overall performance and carrying capacity of the aircraft, and are susceptible to corrosion, requiring additional anti-corrosion measures to extend their service life. Glass fiber fairings have advantages in strength, corrosion resistance, insulation, light weight and heat resistance, but they also have disadvantages such as brittleness and poor wear resistance. Carbon fiber fairings have significant advantages in lightweight, high strength, corrosion resistance and electromagnetic shielding, but disadvantages such as insufficient toughness and difficulty in repair also limit their application.

[0004] Chinese patent CN118189755A discloses a flexible inflatable fairing with separation and fairing integration. The lateral auxiliary support is made of carbon fiber composite material, the nose cone is made of quartz fiber composite material, and the flexible fairing wall is respectively fixed to the fairing nose cone and the fairing rear end connection frame by suturing stainless steel wire. The stainless steel wire is easy to deform under high temperature environment, and its fatigue performance is poor. Although the stainless steel wire is corrosion-resistant, it still needs regular maintenance in some harsh environments. The fairing nose cone, flexible fairing wall, fairing rear end connection frame, and controllable fracture connector are assembled as a whole according to needs. Each component is made by different processes and is not integrally formed. The precision requirements of each component are high, and the processing is difficult. After the assembly is completed, the overall performance of the product itself cannot be guaranteed. The fairing nose cone is made of one of high temperature resistant metal, ceramic-based composite material, and quartz fiber composite material. The flexible fairing wall is made of engineering plastics. The fairing rear end connection frame is made of one of metal material, resin-based carbon fiber composite material, and 3D printed lightweight porous metal material. The overall assembly is heavy. Summary of the invention

[0005] In order to solve the above-mentioned problems such as low mechanical properties, large overall weight, high temperature resistance, poor stability, etc., the present invention provides an integrally formed fairing and a preparation method thereof.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An integrally formed fairing is made of a composite material, wherein the composite material is composed of alternately stacked mesophase asphalt-based carbon fiber prepreg cloth and quartz fiber prepreg cloth, wherein the single layer thickness of the mesophase asphalt-based carbon fiber prepreg cloth is 0.11-0.17 mm; the single layer thickness of the quartz fiber prepreg cloth is 0.03-0.282 mm.

[0008] The fairing is prepared by combining mesophase asphalt-based carbon fiber prepreg with quartz fiber prepreg. The number of plies of the fairing is calculated according to the product thickness, and the plies are laid one by one, that is, one layer of mesophase asphalt-based carbon fiber prepreg and one layer of quartz fiber prepreg.

[0009] The single layer thickness of the mesophase pitch-based carbon fiber prepreg is preferably 0.15 mm, and the single layer thickness of the quartz fiber prepreg is preferably 0.2 mm.

[0010] Preferably, the outermost layer of the composite material is a mesophase pitch-based carbon fiber prepreg. Compared with quartz fiber, mesophase pitch-based carbon fiber has higher strength and stiffness, can withstand greater tensile and compressive forces, and has good thermal conductivity, with a thermal conductivity of more than 5 times that of conductive copper. In addition, mesophase pitch-based carbon fiber also has good corrosion resistance, and is resistant to acid, alkali, salt water and other corrosion.

[0011] Preferably, the mesophase pitch-based carbon fiber prepreg is a sandwich structure formed by mesophase pitch-based carbon fibers and a resin matrix, and the sandwich structure includes an intermediate core layer composed of mesophase pitch-based carbon fibers and an outer layer coated with a resin matrix.

[0012] Preferably, the quartz fiber prepreg cloth is a sandwich structure formed by quartz fiber woven cloth and a resin matrix, the middle core layer of the sandwich structure is the quartz fiber woven cloth, and the outer layer is the coated resin matrix.

[0013] Preferably, the resin matrix is ​​composed of cyanate resin doped with fused quartz ceramic. Cyanate resin is a resin with low dielectric constant and low loss. Fused quartz ceramic has a small thermal expansion coefficient, stable thermal conductivity, stable mechanical properties at high temperatures, and good dielectric properties, which can meet the fairing's requirements for wave transmittance.

[0014] Preferably, the content of fused quartz ceramic in the resin matrix is ​​15%-20wt%.

[0015] Preferably, the content of the cyanate resin matrix in the mesophase pitch-based carbon fiber prepreg is 38-40wt%; the content of the cyanate resin matrix in the quartz fiber prepreg is 30%-50wt%.

[0016] The present invention also provides a method for preparing the above-mentioned integrally formed fairing, comprising the following steps:

[0017] (I) Modification of quartz fiber woven cloth

[0018] The quartz fiber woven cloth was modified using silane coupling agent HK550.

[0019] (II) Preparation of prepreg:

[0020] (2.1) Preparation of film:

[0021] The resin matrix doped with fused quartz ceramic is heated to the coating temperature, and adhesive films of different thicknesses are prepared using an adhesive roller, and PE films and release paper are laid on the upper and lower sides of the adhesive films respectively.

[0022] (2.2) Prepreg process

[0023] Placing the mesophase pitch-based carbon fiber or quartz fiber woven cloth on the unwinding shaft of the prepreg machine, drawing the adhesive film described in step (2.1) from the upper and lower adhesive film rollers, and extruding them at the same time, so that the adhesive film and the mesophase pitch-based carbon fiber form a mesophase pitch-based carbon fiber prepreg with a sandwich structure, and the adhesive film and the quartz fiber woven cloth form a quartz fiber prepreg with a sandwich structure;

[0024] (iii) Lamination;

[0025] (3.1) Laying a first layer of mesophase asphalt-based carbon fiber prepreg on the mold;

[0026] (3.2) Lay out release cloth, breathable felt, and vacuum bag, and perform vacuuming;

[0027] (3.3) After vacuuming is completed, remove the vacuum bag, breathable felt and release cloth;

[0028] (3.4) Laying a quartz fiber prepreg on the first layer of mesophase pitch-based carbon fiber prepreg, and performing vacuum treatment according to steps (3.2) and (3.3);

[0029] (3.5) Calculate the number of plies according to the thickness of the fairing, and repeat steps (3.1) to (3.4) to alternately lay the mesophase asphalt-based carbon fiber prepreg and the quartz fiber prepreg;

[0030] (IV) Curing

[0031] (4.1) Curing the multi-layer prepreg laid in step (iii) at a curing temperature of 120-200°C.

[0032] (4.2) After curing is completed, the temperature is naturally lowered and the mold is removed.

[0033] Preferably, in step (i) the modification process of the quartz fiber woven cloth is to spray the silane coupling agent directly onto the surface of the quartz fiber woven cloth. It can also be soaked, but this method consumes a large amount of coupling agent, which will increase production costs and waste coupling agent.

[0034] Further preferably, the spraying amount of the silane coupling agent is 0.5% of the mass of the quartz fiber woven cloth.

[0035] Preferably, the modification temperature in step (i) is controlled at 100-140°C; more preferably 110°C.

[0036] Preferably, the modification time in step (i) is 20-60 minutes, more preferably 40 minutes.

[0037] Preferably, the prepreg in step (ii) is prepared by a dry process. In particular, there are two types of prepreg production: dry process and wet process. If the wet process is used, the fused quartz ceramic will sink due to its own weight after being added to the resin during preparation due to the high gram weight of the fused quartz ceramic, resulting in uneven distribution of the fused quartz ceramic in the obtained prepreg.

[0038] Preferably, the prepreg fabric production in step (ii) includes the production of adhesive film and prepreg fabric, the adhesive film is prepared by a hot melt adhesive film method, and the prepreg fabric is prepared by a prepreg process. The hot melt adhesive film method has the advantages of precise control of resin content, low volatile matter, and no environmental pollution, and is more widely used.

[0039] Preferably, in step (iii), before laying the first layer of mesophase pitch-based carbon fiber prepreg on the mold, a mold sealant is first applied to the mold. The mold sealant is a polymer sealing composition used to effectively seal invisible microscopic pores in new and refurbished molds.

[0040] Preferably, during the layering in step (iii), the sealing agent is applied 2-3 times.

[0041] Preferably, in step (iii) of layer laying, before laying the first layer of mesophase asphalt-based carbon fiber prepreg on the mold, a high-temperature release agent is applied on the mold coated with the sealing agent.

[0042] Preferably, the high temperature release agent is applied by wiping with a special cloth dipped in the release agent.

[0043] Preferably, during the layering in step (iii), the high temperature release agent is applied 5-6 times.

[0044] Preferably, in step (iii), the demoulding cloth is cut into 1-2 pieces, and should not be cut too much to avoid falling off. The demoulding cloth is in direct contact with the surface of the molded product. If the number of cut pieces is too large, there will be more overlaps between the demoulding cloths, and wrinkles will easily appear if the overlaps are not handled properly; at the same time, there will be more overlap marks left on the product, and the workload of manual post-processing will also increase.

[0045] Preferably, the air-permeable felt is a whole piece to avoid wrinkles at the joints caused by overlapping multiple pieces.

[0046] Preferably, the vacuum bag is a whole piece, and high temperature tape is bonded around the mold so that the vacuum bag can be bonded thereto.

[0047] Preferably, after laying the demoulding cloth, breathable felt and vacuum bag, they are all manually processed. The processing is done for the needs of molding. If the processing is not done and the products are laid directly, resin will accumulate in uneven, wrinkled or raised areas. The second is to prevent the product from bridging and lack of resin. This is especially true at the intersection of the four arcs on the inner cavity of this product.

[0048] Preferably, in the step (iii) of layering, a lay-one-vacuum method is adopted, that is, a layer of prepreg is laid and vacuum is drawn once.

[0049] Preferably, during the vacuuming process after laying the mesophase pitch-based carbon fiber prepreg each time, the total pressure holding time is 15-60 minutes.

[0050] Preferably, during the vacuuming process after laying the quartz fiber prepreg each time, the total pressure holding time is 15-60 minutes.

[0051] Further preferably, the vacuuming process after laying the mesophase pitch-based carbon fiber prepreg is as follows: vacuuming with a vacuum pump, maintaining the pressure after the pressure reaches -0.05MPa, and performing artificial conforming treatment of the vacuum bag again while maintaining the pressure. In particular, the wrinkled areas should be leveled, and attention should be paid to the treatment of the corners, especially to avoid defects such as wrinkles, bulges, and depressions; vacuuming with a vacuum pump, maintaining the pressure after the pressure reaches -0.1MPa, maintaining the pressure for 10-15 minutes, stopping vacuuming, and maintaining the pressure for 10-15 minutes, during which time attention should be paid to whether the pressure changes.

[0052] Further preferably, the vacuuming process after laying the quartz fiber prepreg cloth each time is as follows: vacuuming with a vacuum pump, maintaining the pressure after the pressure reaches -0.05MPa, and while maintaining the pressure, performing manual conformal treatment on the vacuum bag; after the treatment, pressurizing, maintaining the pressure after the pressure reaches -0.1MPa, maintaining the pressure for 20-25 minutes, stopping the vacuuming, and maintaining the pressure for 20-25 minutes, during which time attention should be paid to whether the pressure changes.

[0053] Preferably, the curing process of step (iv) adopts a combination of medium and high temperature curing, that is, curing at medium temperature of 120°C for 1 hour and curing at high temperature of 180°C for 4 hours. During curing, although the prepreg in contact with the release cloth can reach 180°C, if the set temperature is 180°C, since the mold is made of metal, the prepreg in contact with the mold surface will have a contact temperature less than 180°C after receiving the heat transfer from the mold, which will result in insufficient curing of the product.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) The fairing of the present invention optimizes material properties by combining quartz fiber with mesophase pitch-based carbon fiber. Compared with the prior art, the fairing of the present invention has the advantages of high strength and excellent thermal conductivity, as well as light weight, high temperature resistance, and high stability under extreme temperature conditions.

[0056] (2) The present invention adopts an integrated molding process, which is simple to process and has high overall stability.

[0057] (3) The resin matrix of the present invention is doped with 15%-20wt% of fused quartz ceramics, which can improve the heat resistance and mechanical properties of the fairing, maintain a low dielectric constant, reduce dielectric loss, and improve dimensional stability and dimensional accuracy.

[0058] (4) The fairing of the present invention has the effect of making the best use of its strengths and avoiding its weaknesses within the range of the resin matrix content. Mesophase pitch-based carbon fiber has an extremely high thermal conductivity (up to 1000W / m·K or more). Although the thermal conductivity of quartz fiber is not as good as that of carbon fiber, its advantages in high temperature stability can complement those of carbon fiber, thereby improving the heat dissipation efficiency and high temperature resistance of the composite material.

[0059] (5) The prepreg adopts a sandwich structure, which can increase the strength and creep resistance of the prepreg, can withstand a variety of severe weather conditions, and has better mechanical properties.

[0060] (6) Compared with the hand lay-up-molding process, the present invention can avoid the flow and accumulation of resin, uneven resin coating, smoother product surface, and improved finished product quality; it can also avoid the generation of harmful substances and volatile organic compounds in the hand lay-up process. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 Schematic diagram of the sandwich structure of the mesophase pitch-based carbon fiber prepreg fabric of the present invention;

[0062] Figure 2 It is a schematic diagram of the sandwich structure of the quartz fiber prepreg cloth of the present invention;

[0063] Figure 3 It is a schematic diagram of the ply structure of the present invention.

[0064] The following are the descriptions of the reference numerals:

[0065] a, cyanate resin matrix doped with fused quartz ceramic; 1b, mesophase pitch-based carbon fiber; 2b, quartz fiber woven cloth; A, mesophase pitch-based carbon fiber prepreg; B, quartz fiber prepreg. DETAILED DESCRIPTION

[0066] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, some variations and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0067] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0068] The mesophase asphalt-based carbon fiber is prepared according to the invention patent CN116005298A.

[0069] The silane coupling agent used in the embodiment is of model KH550, the sealing agent is of model FK-86, and the high temperature release agent is of model PMR-EZ.

[0070] The samples are the same test pieces made when making the examples and comparative examples, and the size of the test pieces is cut according to the test standards.

[0071] Linear ablation rate and mass ablation rate test equipment and methods:

[0072] Test equipment: Oxygen-acetylene ablation instrument. Oxygen-acetylene ablation instrument is often used to measure the oxyacetylene ablation resistance of samples, and the test is carried out by using the oxyacetylene flame flow as the heat source.

[0073] Test standards and methods: According to GJB323A-96 "Ablation Test Method for Ablative Materials", the sample is ablated by oxygen-acetylene flame flow, and the mass change rate and linear ablation rate per unit time are measured.

[0074] Compression strength test equipment and methods:

[0075] Testing equipment: Compression testing machine. Compression testing machine is used to evaluate the load-bearing capacity and deformation characteristics of materials under compression.

[0076] Test standards and methods: According to GB / T 1448-2005 "Test method for compression properties of fiber reinforced plastics", the sample is placed in a compression testing machine, a vertical compressive force is applied, and the stress-strain behavior of the material is recorded to determine its compressive strength.

[0077] Shear strength test equipment and methods:

[0078] Testing equipment: Shear testing machine.

[0079] Test standard and method: According to JC / T773-2010 "Determination of shear strength of fiber reinforced plastics by short beam method", at room temperature, a shear force is applied in a direction parallel to the plane of the connecting substrate, and the shear strength of the material is recorded. The calculation formula is usually: shear strength = 3F / (4bh), where F is the applied shear force, b is the width of the specimen, and h is the thickness of the specimen.

[0080] Example 1

[0081] A method for preparing an integrally formed fairing comprises the following steps:

[0082] (I) Quartz fiber modification

[0083] Silane coupling agent KH550 was used to modify the quartz fiber woven cloth.

[0084] The silane coupling agent is directly sprayed onto the surface of the quartz fiber woven cloth, and the spraying amount is 0.5% of the mass of the quartz fiber woven cloth.

[0085] The quartz fiber woven cloth sprayed with silane coupling agent was placed in an oven for modification at a temperature of 110°C for 40 minutes. The modified quartz fiber woven cloth was placed in an oven at 150°C for 12 hours and subjected to constant weight detection:

[0086] a. Place the quartz fiber woven cloth into the weighing bottle;

[0087] b. Place the weighing bottle in an electric constant temperature drying oven and heat at 105°C for 1 hour;

[0088] c. After taking it out, put it in a desiccator to cool to room temperature and weigh it;

[0089] d. Repeat steps b and c above until the mass difference between two consecutive weighings does not exceed 2 mg (i.e., constant weight is reached).

[0090] (II) Preparation of prepreg

[0091] (2.1) Film preparation:

[0092] (1) The roller is heated to 120°C.

[0093] (2) The cyanate resin matrix doped with 15 wt% fused silica ceramic is heated to the optimal coating temperature of 75°C.

[0094] (3) The resin matrix is ​​conveyed to the glue coating roller by pressure, and the spacing between the glue coating rollers and the running line speed of the release paper are adjusted. The running line speed is 5-6 m / min to prepare glue films of different thicknesses.

[0095] (4) Use X-ray thickness gauge equipment to instantly detect the surface density of the film.

[0096] The surface density of quartz fiber prepreg film should be controlled at 128g / m 2 ±5, the surface density of carbon fiber prepreg should be controlled at 150g / m 2 ±5.

[0097] (5) The temperature of the film is lowered by a cooling plate to reduce the degree of curing. The temperature of the cooling plate is set to 8°C.

[0098] (6) Place release paper under the film.

[0099] (7) Lay the PE mold on the release paper coated with the film.

[0100] (8) Collect the papers.

[0101] (2.2) Prepreg process:

[0102] (1) Place the mesophase pitch-based carbon fiber or quartz fiber woven cloth on the unwinding reel of the prepreg machine.

[0103] (2) coating, drawing out the pre-made adhesive film with fused quartz ceramic from the upper and lower adhesive film rollers; the adhesive film forms a laminated structure with the mesophase pitch-based carbon fiber and a laminated structure with the quartz fiber woven cloth.

[0104] (3) hot pressing to extrude the laminated structure formed by the adhesive film and the mesophase pitch-based carbon fiber to form a Figure 1 The interphase pitch-based carbon fiber prepreg with a sandwich structure is extruded to form a laminated structure formed by a film and a quartz fiber woven cloth. Figure 2 The quartz fiber prepreg with sandwich structure is shown. The temperature is controlled at 95℃.

[0105] (4) Cooling: passing through a cooling plate to reduce the temperature of the prepreg. The temperature of the cooling plate is controlled at 8°C.

[0106] (5) Lamination: Cover the upper part with a polyethylene film (PE film).

[0107] (6) trimming and rolling to obtain prepreg.

[0108] The content of the resin matrix in the quartz fiber prepreg is 30wt%, and the content of the resin matrix in the mesophase pitch-based carbon fiber prepreg is 38wt%.

[0109] (III) Lamination process

[0110] (1) Mold treatment: Apply 2-3 coats of mold sealant FK-86 on the mold.

[0111] (2) Wipe the mold 5-6 times with a special cloth dipped in high-temperature release agent.

[0112] (3) Laying the mesophase asphalt-based carbon fiber prepreg cloth. At this time, attention should be paid to the combination with the mold. Manually use a defoaming roller to roll it 1-2 times. The surface of the prepreg cloth should be kept flat and wrinkle-free.

[0113] (4) Lay out the release cloth. The release cloth is a regular one. Cut the release cloth into 1-2 pieces. Do not cut too much to avoid it falling off. After laying, perform manual pre-finishing.

[0114] (5) After the release cloth is arranged, the breathable felt is laid. The breathable felt is a whole piece to avoid the appearance of wrinkles at the joints caused by overlapping multiple pieces. After laying, the second manual shaping is carried out.

[0115] (6) Lay the vacuum bag, which is a whole piece. At the same time, high-temperature tape is glued around the mold to facilitate the vacuum bag to be bonded to it. After the vacuum bag is laid, the third manual shaping is performed.

[0116] (7) While laying the vacuum bag, place the vacuum valve inside it.

[0117] (8) Use a vacuum pump to evacuate the bag. When the pressure reaches -0.05MPa, maintain the pressure. While maintaining the pressure, perform artificial shaping of the vacuum bag. In particular, wrinkles should be leveled. At the same time, attention should be paid to the treatment of corners, especially to avoid wrinkles, bulges, and depressions. Use a vacuum pump to evacuate the bag. When the pressure reaches -0.1MPa, maintain the pressure. After 10-15 minutes, stop evacuating the bag and maintain the pressure for 10-15 minutes. During this period, pay attention to whether the pressure changes.

[0118] (9) After vacuuming is completed, remove the vacuum bag, breathable felt, and release cloth.

[0119] (10) Check whether the outer surface of the carbon fiber prepreg is flat. If there are wrinkles, level it.

[0120] (11) Lay the quartz fiber prepreg on the laid mesophase pitch-based carbon fiber prepreg, and follow the same steps as the first layer of carbon fiber prepreg. When evacuating, special attention should be paid: use a vacuum pump to evacuate, and after the pressure reaches -0.05MPa, maintain the pressure. While maintaining the pressure, perform manual shaping of the vacuum bag. After the pressure reaches -0.1MPa, maintain the pressure. After maintaining the pressure for 20-25 minutes, stop evacuating and maintain the pressure for 20-25 minutes. During this period, pay attention to whether the pressure changes.

[0121] (12) Calculate the number of plies based on product thickness, such as Figure 3 As shown, the thickness of the fairing is 3mm, 10 layers of mesophase asphalt-based carbon fiber prepreg are laid, and the single layer is 0.15mm thick. 9 layers of quartz fiber prepreg are laid, and the single layer is 0.2mm thick. After calculation, the ply thickness is 3.3mm. Considering the vacuum process, the prepreg has a certain shrinkage, and this shrinkage is temporarily considered to be 10%, that is, the final thickness is 3.3-3.3*10%. And lay one by one, that is, lay one layer of mesophase asphalt-based carbon fiber prepreg, and lay one layer of quartz fiber prepreg. The outermost layer is also mesophase asphalt-based carbon fiber prepreg. During the plying process, lay one and draw one, that is, lay one layer of prepreg and draw vacuum once.

[0122] (IV) Curing

[0123] The laid products are cured at 120℃ for 1 hour and 180℃ for 4 hours. After the curing is completed, the temperature is naturally lowered until the mold is removed.

[0124] The mass ablation rate of the product was measured to be 0.021 g / s, the linear ablation rate was 0.04 mm / s, the compressive strength was 781.4 MPa, and the shear strength was 74.2 MPa.

[0125] Example 2

[0126] The other parts are the same as Example 1, except that in step 2, the resin matrix is ​​a fused quartz ceramic doped with 17wt%, the content of the resin matrix in the quartz fiber prepreg is 35wt%, and the content of the resin matrix in the mesophase pitch-based carbon fiber prepreg is 39wt%. The mass ablation rate of the product is measured to be 0.018g / s, the line ablation rate is 0.038mm / s, the compressive strength is 783.6MPa, and the shear strength is 75.3MPa.

[0127] Example 3

[0128] The other parts are the same as Example 1, except that in step 2, the resin matrix is ​​a fused quartz ceramic doped with 20wt%, the content of the resin matrix in the quartz fiber prepreg is 40wt%, and the content of the resin matrix in the mesophase pitch-based carbon fiber prepreg is 40wt%. The mass ablation rate of the product is measured to be 0.013g / s, the line ablation rate is 0.042mm / s, the compressive strength is 774.2MPa, and the shear strength is 73.1MPa.

[0129] Comparative Example 1

[0130] The other aspects are the same as those of Example 2, except that in step 2, the cyanate resin matrix content in the quartz fiber prepreg is 25wt%. The mass ablation rate of the product was measured to be 0.032g / s, the linear ablation rate was 0.0642mm / s, the compressive strength was 741.6MPa, and the shear strength was 68.5MPa.

[0131] Comparative Example 2

[0132] The other aspects are the same as those of Example 2, except that in step 2, the content of the resin matrix in the mesophase pitch-based carbon fiber prepreg is 35wt%. The mass ablation rate of the product was measured to be 0.031g / s, the linear ablation rate was 0.0621mm / s, the compressive strength was 732.8MPa, and the shear strength was 67.4MPa.

[0133] Comparative Example 3

[0134] The other parts are the same as those in Example 2, except that in step 2, the content of fused quartz ceramic in the resin matrix is ​​13wt%. The mass ablation rate of the product is measured to be 0.027g / s, the linear ablation rate is 0.0554mm / s, the compressive strength is 772.4MPa, and the shear strength is 73.2MPa.

[0135] Comparative Example 4

[0136] The other aspects are the same as those of Example 2, except that no fused quartz ceramic is added to the resin in step 2. The mass ablation rate of the product was measured to be 0.041 g / s, the linear ablation rate was 0.073 mm / s, the compressive strength was 770.5 MPa, and the shear strength was 71.4 MPa.

[0137] Comparative Example 5

[0138] Hand lay-up-molding process:

[0139] (1) Mold treatment: Apply 2-3 coats of mold sealant FK-86 on the mold.

[0140] (2) Apply 5-6 coats of high-temperature release agent to the mold. The mold is divided into an upper mold and a lower mold, and the lower mold is used when laying the layers.

[0141] (3) Weigh each piece of cut mesophase pitch-based carbon fiber woven cloth and quartz fiber woven cloth and record them in a table to calculate the resin consumption of each layer of fiber cloth.

[0142] (4) The first layer is an intermediate phase asphalt-based carbon fiber woven cloth, which is manually coated with resin on both sides. The resin is doped with 15% fused quartz ceramics. The coating should be even to avoid resin accumulation. When placing it into the mold, it is laid from the middle to the two ends, paying attention to the combination of the first layer and the mold. After laying, use a defoaming roller to manually roll it 2-3 times to avoid bulging of the woven cloth. The cyanate resin matrix content in the intermediate phase asphalt-based carbon fiber prepreg is 38wt%.

[0143] (5) When laying the quartz fiber woven cloth, apply the resin manually on both sides. The resin is doped with 15% fused quartz ceramics and should be applied evenly. When placing it in the mold, lay it from the middle to the two ends, paying attention to its combination with the first layer of carbon fiber. The cyanate resin matrix content in the quartz fiber prepreg is 30wt%.

[0144] (6) Same as step (iii) (12) of Example 1, layer laying.

[0145] (7) After laying, close the upper mold. Before closing the upper mold, apply 2-3 coats of mold sealing agent FK-86 and 5-6 coats of high-temperature mold release agent.

[0146] (8) After the mold is closed, the mold is placed in a molding machine for molding. The temperature setting during molding is based on the mold surface temperature, and a temperature measuring instrument is used to measure the temperature to ensure that the temperature is 170°C.

[0147] (9) At the beginning of molding, after 10-20 seconds of molding, demolding is carried out and the upper mold is lifted. This operation is repeated twice.

[0148] (10) After curing is completed, the temperature is naturally cooled until demolding.

[0149] The mass ablation rate of the product was measured to be 0.036 g / s, the linear ablation rate was 0.0661 mm / s, the compressive strength was 754.3 MPa, and the shear strength was 72.8 MPa.

[0150] By comparison, the content of fused quartz ceramic is 17wt%, the content of cyanate resin in the intermediate phase asphalt-based carbon fiber prepreg is 35wt%, and the content of cyanate resin in the quartz fiber prepreg is 39wt%. At this time, the product quality ablation rate, linear ablation rate, compressive strength and shear strength are optimal.

[0151] Increasing the content of fused quartz ceramics can improve the density and mechanical strength of the material, reduce the mass ablation rate and line ablation rate, while maintaining a low dielectric constant and good thermal stability. When the content of fused quartz ceramics is higher than 20%, the strength of the product will be reduced, resulting in a decrease in the mechanical properties of the material, and an increase in its thermal expansion coefficient, which will cause the material to deform and crack at high temperatures, affecting the structural stability and service life of the fairing; when it is lower than 15%, it may result in a lower thermal expansion coefficient of the material, but at the same time it may affect the mechanical strength and hardness of the material. At the same time, low content of fused quartz may cause the density of the material to decrease, thereby affecting its overall performance and application effect.

[0152] As the carbon fiber content increases, the thermal conductivity of the material improves, and the heat can be transferred from the ablation surface to the inside more quickly, thereby reducing the temperature of the ablation surface, reducing the occurrence of mass ablation and line ablation, while improving the compression strength and shear strength of the composite material, and significantly improving the thermal conductivity of the material.

[0153] Increasing the quartz fiber content generally increases the compressive and shear strengths of the composites, while decreasing the thermal conductivity of the composites.

[0154] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An integrally formed fairing, characterized in that: The composite material is prepared by alternating layers of mesophase asphalt-based carbon fiber prepreg cloth and quartz fiber prepreg cloth; wherein the single layer thickness of the mesophase asphalt-based carbon fiber prepreg cloth is 0.11-0.17 mm, and the single layer thickness of the quartz fiber prepreg cloth is 0.03-0.282 mm.

2. The fairing according to claim 1, characterized in that: The single-layer thickness of the mesophase pitch-based carbon fiber prepreg is 0.15 mm, and the single-layer thickness of the quartz fiber prepreg is 0.2 mm.

3. The fairing according to claim 1, characterized in that: The outermost layer of the composite material is mesophase asphalt-based carbon fiber prepreg.

4. The fairing according to claim 2, characterized in that: The mesophase asphalt-based carbon fiber prepreg is a sandwich structure formed by mesophase asphalt-based carbon fiber and a resin matrix, and the sandwich structure includes an intermediate core layer composed of mesophase asphalt-based carbon fiber and an outer layer coated with a resin matrix; the quartz fiber prepreg is a sandwich structure formed by quartz fiber woven cloth and a resin matrix, and the intermediate core layer of the sandwich structure is quartz fiber woven cloth, and the outer layer is a coated resin matrix.

5. The fairing according to claim 4, characterized in that: The resin matrix is ​​composed of cyanate resin doped with fused quartz ceramics; preferably, the content of fused quartz ceramics in the resin matrix is ​​15%-20wt%.

6. The fairing according to claim 5, characterized in that: The content of the cyanate resin matrix in the mesophase pitch-based carbon fiber prepreg is 38-40wt%; the content of the cyanate resin matrix in the quartz fiber prepreg is 30%-50wt%.

7. The method for preparing the fairing according to any one of claims 1 to 6, characterized in that: The following steps are involved: (I) Modification of quartz fiber woven cloth The quartz fiber woven cloth was modified using silane coupling agent HK550; (II) Preparation of prepreg: (2.1) Preparation of film: The resin matrix doped with fused quartz ceramic is heated to the coating temperature, and adhesive films of different thicknesses are prepared using an adhesive roller, and PE films and release paper are laid on the upper and lower sides of the adhesive films respectively; (2.2) Prepreg process Placing the mesophase pitch-based carbon fiber or quartz fiber woven cloth on the unwinding shaft of the prepreg machine, drawing the adhesive film described in step (2.1) from the upper and lower adhesive film rollers, and extruding them at the same time, so that the adhesive film and the mesophase pitch-based carbon fiber form a mesophase pitch-based carbon fiber prepreg with a sandwich structure, and the adhesive film and the quartz fiber woven cloth form a quartz fiber prepreg with a sandwich structure; (iii) Lamination; (3.1) Laying a first layer of mesophase asphalt-based carbon fiber prepreg on the mold; (3.2) Lay out release cloth, breathable felt, and vacuum bag, and perform vacuuming; (3.3) After vacuuming is completed, remove the vacuum bag, breathable felt and release cloth; (3.4) Laying a quartz fiber prepreg on the first layer of mesophase pitch-based carbon fiber prepreg, and performing vacuum treatment according to steps (3.2) and (3.3); (3.5) Calculate the number of plies according to the thickness of the fairing, and repeat steps (3.1) to (3.4) to alternately lay the mesophase asphalt-based carbon fiber prepreg and the quartz fiber prepreg; (IV) Curing (4.1) curing the multi-layer prepreg laid in step (iii) at a curing temperature of 120-200° C.; (4.2) After curing is completed, the temperature is naturally lowered and the mold is removed.

8. The method for preparing a fairing according to claim 7, characterized in that: Step (i) The modification process of the quartz fiber woven cloth is as follows: spraying the silane coupling agent directly onto the surface of the quartz fiber woven cloth, controlling the modification temperature at 100-140° C., and the modification time at 20-60 min; the modification temperature is preferably 110° C., and the modification time is preferably 40 min.

9. The method for preparing a fairing according to claim 7, characterized in that: In step (iii) of laying, the demoulding cloth is cut into 1-2 pieces, the breathable felt is a whole piece, and the vacuum bag is a whole piece; the vacuuming is carried out in a lay-one-drain-one manner, that is, a layer of prepreg is laid and vacuuming is carried out once; after laying the demoulding cloth, breathable felt and vacuum bag, manual handling is performed.

10. The method for preparing a fairing according to claim 7, characterized in that: The curing process of step (iv) adopts a mode combining medium and high temperature curing; preferably, the curing conditions are medium temperature 120° C. curing for 1 hour and high temperature 180° C. curing for 4 hours.

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