Porous composite material structure and preparation method thereof

Abstract

The invention discloses a porous composite material structure and a preparation method thereof, and the preparation method comprises the following steps: forming a through hole in a woven body by adopting a sewing process of a water-soluble fiber base line or a needling process, and then performing impregnation treatment on the woven body by injecting resin to obtain a porous prepreg; after the porous prepreg is cured and formed, the water-soluble fiber base line or needle is separated from the porous prepreg to obtain a porous composite material structure; according to the preparation method, the porous structure of the composite material can be rapidly and efficiently obtained at low cost, the process is simple, and the damage to the performance and the service life of the composite material caused by traditional machining punching or laser machining can be avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and in particular relates to the technical field of preparing porous composite material structures. Background Art

[0002] Lightweight structure is the goal that aircraft are constantly pursuing. At present, new composite materials represented by carbon fiber reinforced composite materials have the advantages of high specific strength and good designability, and are widely used in the aerospace field. As the speed of aircraft continues to rise, the operating temperature of its surface continues to rise. Excessive temperature will reduce the mechanical properties and service life of resin-based composite materials.

[0003] Transpiration cooling technology is an active thermal protection technology with extremely high cooling efficiency. It can effectively reduce the temperature of the solid wall of the aircraft and increase the application temperature range of composite materials. The design and preparation of the porous structure required for transpiration cooling is relatively difficult, which restricts its further promotion and application. For resin-based composite structural parts, their porous structure can be achieved through mechanical drilling, laser processing, etc. However, its processing efficiency is low, the processing cost is high, and it is difficult to achieve for microporous capillary structures with a large depth-to-diameter ratio.

[0004] Therefore, it is necessary to propose a new technical solution to solve the above technical problems. Summary of the invention

[0005] Purpose of the invention: In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing a porous composite material structure that can achieve efficient and low-cost processing of a microporous capillary structure.

[0006] The invention also provides a porous composite material structure obtained by the preparation method.

[0007] In order to achieve the above-mentioned purpose, the technical scheme that can be adopted in the method for preparing the porous composite material structure provided by the present invention is as follows:

[0008] A method for preparing a porous composite material structure comprises the following steps:

[0009] (1) providing a braided body;

[0010] (2) forming a plurality of through holes in the braided body, wherein the through holes are formed by a stitching process of a water-soluble fiber base or by a needle punching process, and the water-soluble fiber base or needle in this step is not separated from the braided body;

[0011] (3) impregnating the braided body with the water-soluble fiber base or needle by injecting resin to obtain a porous prepreg;

[0012] (4) curing and forming the porous prepreg;

[0013] (5) The water-soluble fiber base line or needle is detached from the porous prepreg to allow through holes to penetrate the porous prepreg vertically.

[0014] Furthermore, in step (2), a plurality of through holes are formed in the woven body by sewing a water-soluble fiber base line, and in step (5), the porous prepreg obtained in the step is placed in water to dissolve the water-soluble fiber base line to obtain the through holes.

[0015] Furthermore, in step (2), the water-soluble fiber base line is sewn into the braided body by a reciprocating sewing process, so that the obtained through holes are arranged in rows with equal spacing and in parallel.

[0016] Furthermore, in step (2), the water-soluble fiber base line is sewn into the woven body by a single-thread chain stitching process, so that the obtained through holes are grouped in pairs to form a plurality of through hole groups, each group of through hole groups are arranged in rows equidistant and in parallel, and the two through holes in each group of through hole groups are arranged in parallel.

[0017] Furthermore, in step (2), the water-soluble fiber base line is sewn into the braided body by a double-thread lock stitching process, so that the resulting through hole is an X-shaped hole, each through hole has two outlets on the upper surface of the braided body and two outlets on the lower surface of the braided body, and these four outlets are interconnected.

[0018] Furthermore, the diameter of the water-soluble fiber bundle is 0.1 to 0.5 mm.

[0019] Furthermore, when the composite material is heated and cured by a stitching process using water-soluble fibers as the base line, the temperature should be less than 150°C.

[0020] Furthermore, when the porous prepreg is placed in water to dissolve the water-soluble fiber base line, the water bath dissolution temperature is controlled at the dissolution temperature of the water-soluble fiber base line. During the water bath dissolution, the porous prepreg is placed in an ultrasonic vibration device to accelerate the dissolution rate of the water-soluble fiber base line through ultrasonic vibration.

[0021] Furthermore, in step (2), the through holes are formed by a needle punching process using a plurality of needles, wherein the needles are metal microneedles, and the diameter of each metal microneedle is 0.1 to 0.5 mm.

[0022] Compared with the prior art, the beneficial effects of the present invention are: compared with the prior art in which a porous structure of a composite material is manufactured by mechanical drilling or laser processing, the present invention adopts a suturing process of a water-soluble fiber base line or forms through holes by a needle punching process, especially the water-soluble fiber base line or needle is a slender structure, which can realize a microporous (through hole) capillary structure with a relatively large depth-to-diameter ratio; thus, the preparation method can realize the rapid, efficient and low-cost acquisition of a porous structure of a composite material, the process is simple, and it can also avoid the damage to the performance and service life of the composite material caused by traditional mechanical processing or laser processing.

[0023] The present invention also provides a porous composite material structure, which is prepared by the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a cross-sectional view of the stitching alignment of a composite material preform using a single-line reciprocating stitching process;

[0025] Figure 2 A cross-sectional view of a porous composite material formed by a single-line reciprocating stitching process;

[0026] Figure 3 It is a cross-sectional view of the stitching alignment of a composite material preform using a single-line chain stitching process;

[0027] Figure 4 This is a partial enlarged view of the stitching alignment of the composite material preform using the single-line chain stitching process;

[0028] Figure 5 is a cross-sectional view of a porous composite material formed by a single-line chain stitching process;

[0029] Figure 6 It is a cross-sectional view of the stitching alignment of a composite material preform using a double-thread lock stitching process;

[0030] Figure 7 is a cross-sectional view of a porous composite material formed by a double-thread lock stitching process;

[0031] Figure 8 This is a structural diagram of the high-strength metal microneedle acupuncture process.

[0032] In the figure: 10, water-soluble fiber base line; 20, composite material braid; 30, composite material; 40, porous structure; 50, needle. DETAILED DESCRIPTION

[0033] In order to make the above features and advantages of the present invention more obvious and easy to understand, embodiments will be described in detail below with reference to the accompanying drawings.

[0034] Example 1

[0035] This embodiment adopts the suture process based on water-soluble fiber as the base line proposed in the present invention to prepare a porous composite material structure, which specifically includes the following steps:

[0036] (1) According to the composite material structure to be woven, a corresponding three-dimensional weaving pattern is selected, and a composite material braided body 20 is obtained by three-dimensional weaving; the main fiber of the composite material is selected from carbon fibers with medium to high tensile strength and modulus, such as T700, T800, T1100, etc.; T700 carbon fibers are selected in this embodiment;

[0037] (2) The braided body 20 obtained in step (1) is formed into a plurality of through holes by a stitching process using a water-soluble fiber base line 10. The water-soluble fiber base line in this step is not separated from the braided body. The water-soluble fiber base line 10 is selected from polyvinyl alcohol fiber as the base line, and a preform is obtained by a reciprocating stitching process. The corresponding stitching line diagram is shown in FIG. Figure 1 As shown, the obtained through holes are arranged in rows with equal spacing and in parallel; the dissolution temperature of the selected polyvinyl alcohol fiber is about 41 to 70°C, and the fiber bundle diameter is 0.1 to 0.5 mm;

[0038] (3) placing the preform in step (2) into a mold, and then injecting resin for pre-impregnation, paying attention to the temperature and time of the pre-impregnation to ensure that the epoxy resin can fully penetrate into the gaps in the fiber bundles; the resin is selected from medium- and low-temperature resins, such as medium-temperature epoxy resin, low-temperature epoxy resin, acrylic resin, ultraviolet curing resin, etc.; medium-temperature epoxy resin is selected in this embodiment;

[0039] (4) The prepreg in step (3) is heated and cured to form a mold. Vacuum assisted composite material (VARI) molding technology or resin film infiltration process (RFI) molding technology can be used. In this embodiment, vacuum assisted composite material (VARI) molding technology is used. The temperature is controlled below 150° C. After the prepreg is heated and cured, demolding is performed;

[0040] (5) Mechanically processing the surface of the composite material 30 obtained in step (4) to remove the excess and expose the polyvinyl alcohol fibers 10; placing the mechanically processed composite material 30 in water, controlling the water temperature to be 41 to 70° C., and performing ultrasonic vibration for at least 30 minutes by an ultrasonic device to accelerate the dissolution of the polyvinyl alcohol fibers 10. After the polyvinyl alcohol fibers 10 are completely dissolved, drying the composite material to obtain a porous structure 50 arranged in rows with equal spacing and parallel arrangement, such as Figure 2 As shown, since the fiber bundle diameter of the water-soluble fiber base 10 is 0.1-0.5 mm, the through holes obtained after dissolution can form a microporous (through hole) capillary structure with a relatively large depth-to-diameter ratio.

[0041] Example 2

[0042] This embodiment adopts the stitching process based on water-soluble fiber as the base line proposed by the present invention to prepare a porous composite material structure.

[0043] The difference between this embodiment and embodiment 1 is that the stitching process in step (2) adopts a single-line chain stitching process different from that in embodiment 1, that is, each time a stitch is made, a circle of water-soluble fiber 10 is pulled into the loop formed by the previous circle of water-soluble fiber 10, thereby forming a chain structure, and its routing in the composite material braided body 20 is as follows: Figure 3 As shown, the local enlarged picture is as follows Figure 4As shown, the composite material 30 and the porous structures 40 arranged in rows and evenly distributed in pairs are prepared by the same curing process and water bath dissolving water-soluble fiber process as in Example 1, as shown in FIG. Figure 5 As shown. The through holes obtained by the single-line chain stitching process are grouped in pairs to form a plurality of through hole groups, each through hole group is arranged in rows equidistant and parallel, and the two through holes in each through hole group are arranged in parallel. And the spacing between the two through holes in each through hole group is smaller than the spacing between two adjacent through hole groups.

[0044] Except for step (2), the other steps of this embodiment are the same as those of embodiment 1.

[0045] Example 3

[0046] This embodiment adopts the stitching process based on water-soluble fiber as the base line proposed by the present invention to prepare a porous composite material structure.

[0047] The difference between this embodiment and the first and second embodiments is that the suturing process adopts a double-thread lock suturing process different from the first and second embodiments, that is, at each stitch, the upper water-soluble fiber 10 and the lower water-soluble fiber 10 are intertwined together and oriented in the same direction, thereby forming a lock structure, and the routing of the composite material braid 20 is as shown in FIG. Figure 6 As shown, the composite material 30 and the X-shaped porous structure 40 evenly distributed in rows and columns are prepared by the same curing process and water bath dissolving water-soluble fiber process as in embodiment 1, as shown in FIG. Figure 7 shown. Figure 7 The X-shaped hole has two outlets on the upper surface of the braided body 20 and two outlets on the lower surface of the braided body 20, and these four outlets are interconnected.

[0048] Except for step (2), the other steps of this embodiment are the same as those of embodiments 1 and 2.

[0049] Example 4

[0050] This embodiment adopts the high-strength metal microneedle acupuncture process proposed in the present invention to prepare a porous composite material structure, which specifically includes the following steps:

[0051] (1) First, a three-dimensional braiding method similar to step (1) in Example 1 is used to obtain a braided body;

[0052] (2) using a plurality of needles 50 to form the through holes by a needle punching process, wherein the needles 50 are metal microneedles made of steel with high bending and tensile strength, such as Q345, Q420, Q460, 304, 316, etc.; the diameter of each metal microneedle is 0.1 to 0.5 mm;

[0053] The mold release agent is evenly applied on the surface of the needle 50, and the needle 50 is evenly inserted into the gaps between the carbon fiber bundles of the composite material braided body 20. Figure 8 As shown;

[0054] (3) impregnating the braided body 20 with the needles 50 by injecting resin to obtain a porous prepreg;

[0055] (4) curing and forming the porous prepreg; the curing and forming adopts a composite material vacuum assisted (VARI) forming technology or a resin film infiltration process (RFI) forming technology to cure the resin;

[0056] (5) Pull out the needle 50 on the composite material formed by curing in step (4). When pulling out, hold the circular groove at one end of the needle 50 and lift it up to obtain a porous composite material. The porous structure 40 finally formed is the same as that in Example 1, and is also composed of rows of equidistant and parallel through holes (such as Figure 2 As shown). Since the diameter of the metal microneedle is 0.1-0.5 mm, the through hole obtained after the needle is pulled out can form a micropore (through hole) capillary structure with a relatively large depth-diameter ratio.

[0057] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions of the technical solutions of the present invention made by ordinary technicians in the field should all be included in the protection scope of the present invention. The protection scope of the present invention shall be based on what is defined in the claims.

Claims

1. A method for preparing a porous composite material structure, characterized in that: The following steps are included: (1) Providing a braid (20); (2) forming a plurality of through holes in the braided body (20), wherein the through holes are formed by a stitching process using a water-soluble fiber base line (10) or by a needle punching process, and in this step, the water-soluble fiber base line (10) or the needle (50) is not separated from the braided body (20); (3) impregnating the braided body (20) with the water-soluble fiber base wire (10) or the needle (50) by injecting resin to obtain a porous prepreg; (4) curing and forming the porous prepreg; (5) The water-soluble fiber base wire or needle is detached from the porous prepreg so that the through hole (40) penetrates the porous prepreg from top to bottom.

2. The method for preparing the porous composite material according to claim 1, characterized in that: In step (2), a plurality of through holes are formed in the woven body (20) by sewing the water-soluble fiber base (10). In step (5), the porous prepreg obtained in step (4) is placed in water to dissolve the water-soluble fiber base (10) to obtain through holes.

3. The method for preparing a porous composite material structure according to claim 2, characterized in that: In step (2), the water-soluble fiber base line (10) is sewn into the braided body (20) by a reciprocating sewing process, so that the obtained through holes are arranged in rows with equal distances and in parallel.

4. The method for preparing a porous composite material structure according to claim 2, characterized in that: In step (2), the water-soluble fiber base line (10) is sewn into the woven body (20) by a single-thread chain stitching process, so that the obtained through holes are grouped in pairs to form a plurality of through hole groups, each group of through hole groups are arranged in rows equidistant and in parallel, and the two through holes in each group of through hole groups are arranged in parallel.

5. The method for preparing a porous composite material structure according to claim 2, characterized in that: In step (2), the water-soluble fiber base line (10) is sewn into the braid (20) by a double-thread lock stitching process, so that the resulting through hole is an X-shaped hole, each through hole has two outlets on the upper surface of the braid (20) and two outlets on the lower surface of the braid (20), and these four outlets are interconnected.

6. The method for preparing a porous composite material structure according to any one of claims 1 to 5, characterized in that: The water-soluble fiber is medium-temperature soluble polyvinyl alcohol fiber, and the fiber bundle diameter is 0.1-0.5 mm.

7. The method for preparing a porous composite material structure according to claim 6, characterized in that: When the composite material is heated and cured by a stitching process using water-soluble fibers as the base line, the temperature should be less than 150°C.

8. The method for preparing a porous composite material structure according to claim 2, characterized in that: When the porous prepreg is placed in water to dissolve the water-soluble fiber base line (10), the water bath dissolution temperature is controlled at the dissolution temperature of the water-soluble fiber base line (10). During the water bath dissolution, the porous prepreg is placed in an ultrasonic vibration device to accelerate the dissolution rate of the water-soluble fiber base line (10) through ultrasonic vibration.

9. The method for preparing a porous composite material structure according to claim 1, characterized in that: In step (2), the through holes are formed by a needle punching process using a plurality of needles (50), wherein the needles (50) are metal microneedles, and each metal microneedle has a diameter of 0.1 to 0.5 mm.

10. A porous composite material structure, characterized in that: It is characterized in that The method is prepared by the method according to any one of claims 1 to 9.

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