A multi-gradient heat-resistant and load-bearing integrated composite material and its preparation method

Abstract

The present invention discloses a multi-gradient heat-resistant and load-bearing integrated composite material, comprising an upper panel, a bridge-shaped web, a sandwich insulation material, and a lower panel. The upper plane of the bridge-shaped web is connected to the upper panel via a secondary bonding process, and the lower foot plane of the bridge-shaped web is vertically connected to the lower panel via a bonding co-curing process. The bridge-shaped web is a multi-gradient composite bridge structure, comprising an ablation-resistant structural layer, a thermal insulation structural layer, and a load-bearing structural layer, which are laid out from top to bottom using prepreg to form a preform. The ablation-resistant structural layer and the thermal insulation structural layer are arranged in a gradually decreasing structure from top to bottom. The bottom end of the ablation-resistant structural layer is laid on the thermal insulation structural layer, and the bottom end of the thermal insulation structural layer is laid on the load-bearing structural layer. The end of the load-bearing structural layer is connected to the lower panel at a 90-degree angle. The material is lightweight and has excellent load-bearing and thermal insulation properties.

Description

Technical Field

[0001] The present invention belongs to the field of thermal protection technology, and in particular relates to a multi-gradient thermal protection and load-bearing integrated composite material and a preparation method thereof. Background Art

[0002] Hypersonic spacecraft have a very harsh thermal-mechanical service environment. The structure of a hypersonic spacecraft should have excellent structural mechanical properties while having thermal protection. With the continuous development of new materials and new technologies, integrated heat protection and load-bearing technology has provided a new development idea for spacecraft to cope with harsh environments during ultra-high-speed flight. Integrated heat protection and load-bearing technology means that the thermal protection system can withstand other flight loads at the same time while completing the heat insulation function. At present, lightweight integrated heat protection and load-bearing composite materials have been used in various types of hypersonic aircraft. Among them, the corrugated sandwich integrated thermal protection structure integrates low density, high strength, high temperature resistance and other properties, and has gradually become the most common integrated heat protection and load-bearing product in spacecraft. The optimization and improvement of its lightweight, load-bearing and thermal insulation properties are the current research focus.

[0003] Chinese patent application number CN113148108A applies to a double-layer corrugated sandwich structure with integrated insulation and load-bearing capabilities. The double-layer corrugated sandwich structure comprises parallel upper and lower panels, identical upper and lower corrugated sandwich structures, and a central partition connecting the two layers. Both the upper and lower corrugated sandwich structures include a load-bearing structure and an insulation layer. The load-bearing structure is formed by multiple webs with parallel central axes, forming multiple insulation cavities. Adjacent webs are connected to each other at their ends via connecting plates, forming a single unit. The insulation cavities are filled with insulation material to form an insulation layer. This method uses a double-layer corrugated sandwich core to replace conventional single-layer corrugated panels, effectively improving thermal short-circuiting effects. However, the double-layer structure directly improves product quality, and the more complex structure also presents difficulties in product molding and manufacturing.

[0004] Chinese patent application number CN105083528A discloses a thermal protection device comprising an upper panel, a bottom panel, an upper corrugated plate layer composed of a plurality of upper corrugated plates arranged in sequence, and a lower corrugated plate layer composed of a plurality of lower corrugated plates arranged in sequence. The upper corrugated plate layer is disposed above the lower corrugated plate layer, and the upper and lower corrugated plate layers are arranged in an alternating pattern. The lower ends of the upper corrugated plates are connected to the upper ends of the lower corrugated plates via a thermal insulation and load-bearing coordinated bolt connection structure. The thermal insulation and load-bearing coordinated bolt connection structure comprises connecting bolts, an upper thermal insulation washer, a middle thermal insulation washer, a lower thermal insulation washer, and a connecting nut. The gap between the upper panel and the lower end of the upper corrugated plate is filled with a high-temperature resistant insulation material, and the gap between the bottom panel and the upper end of the lower corrugated plate is filled with a medium-temperature resistant insulation material. This invention reduces the thermal short-circuiting effect by installing thermal insulation gaskets and washers, which increases the complexity and quality of the structure and may also affect the tightness of the insulation material.

[0005] Therefore, a material with light weight, excellent load-bearing and thermal insulation properties is needed. Summary of the Invention

[0006] In order to solve the above problems, the present invention aims to provide a multi-gradient heat-resistant and load-bearing integrated composite material and a preparation method thereof.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a multi-gradient heat-resistant and load-bearing integrated composite material, comprising an upper panel, a bridge-shaped web, a sandwich insulation material, and a lower panel. The upper surface of the bridge-shaped web is connected to the upper panel by a secondary bonding process, and the lower surface of the bridge-shaped web foot is vertically connected to the lower panel by a bonding co-curing process.

[0008] The bridge-type web is a multi-gradient composite bridge structure, which is formed by paving the ablation-resistant structural layer, the thermal insulation structural layer and the load-bearing structural layer from top to bottom using prepreg to form a preform. The ablation-resistant structural layer and the thermal insulation structural layer are distributed in a gradually decreasing structure from top to bottom. The bottom end of the ablation-resistant structural layer is paved on the thermal insulation structural layer, and the bottom end of the thermal insulation structural layer is paved on the load-bearing structural layer. The end of the load-bearing structural layer is in contact with the lower panel at 90 degrees.

[0009] The bridge-shaped web is provided with a 180° top bonding structural surface, and the area of ​​the top bonding structural surface accounts for 5% to 9% of the upper surface area of ​​the bridge-shaped web.

[0010] Taking the overall height of the bridge-type web as the reference surface, the height of the ablation-resistant structural layer is 60% to 70% of the height of the bridge-type web, and the thickness decreases from the top layer to both sides of the ablation-resistant structural layer, and decreases from the maximum thickness of the layer to 0mm; the height of the thermal insulation structural layer is 70% to 90% of the height of the bridge-type web, and the thickness decreases from the top layer to both sides of the thermal insulation structural layer, and decreases from the maximum thickness of the layer to 0mm; the thickness of the load-bearing structural layer remains unchanged from top to bottom.

[0011] The maximum thickness of the bridge-type web is 1.5 to 3.8 mm, of which the ablation-resistant structural layer is made of quartz / phenolic prepreg, and the maximum thickness of the layer is 0.2 to 1 mm; the thermal insulation structural layer is made of glass fiber / phenolic prepreg, and the maximum thickness of the layer is 0.3 to 0.8 mm; the load-bearing structural layer is made of carbon fiber / high-temperature epoxy prepreg, and the thickness of the layer is 1 to 2 mm.

[0012] The upper panel is formed by paving and curing quartz fiber / phenolic prepreg, and the thickness of the panel is 1.5-4 mm.

[0013] The lower panel is formed by paving and curing carbon fiber / high-temperature epoxy prepreg, and the panel thickness is 1 to 3 mm.

[0014] The high-temperature epoxy resin matrix and the phenolic resin matrix in the carbon fiber / high-temperature epoxy prepreg, the quartz fiber / phenolic prepreg and the glass fiber / phenolic prepreg have similar glass transition temperatures.

[0015] The sandwich insulation material is filled in the gaps between the upper panel, the bridge-shaped web and the lower panel. The core insulation material is a combination of one or more of alumina fiber insulation material, ultrafine glass fiber material and silica aerogel insulation felt.

[0016] A method for preparing a multi-gradient heat-resistant and load-bearing integrated composite material comprises the following steps:

[0017] Step 1: Prepare the bridge-shaped web: prepare the mold, prepare the prepreg, apply the release agent, cut the prepreg, lay the bottom carbon fiber / high-temperature epoxy prepreg, vacuum pre-compact, lay the glass fiber / phenolic prepreg, hot compact, lay the top quartz fiber / phenolic prepreg, hot compact, bag and vacuum, cure, demould, trim and polish;

[0018] Step 2: Prepare the upper panel: The upper panel is formed into a flat plate with the required size by using the paving-autoclave molding process;

[0019] Step 3: Prepare the lower panel and bond it to the bridge web: Pre-compact the carbon fiber prepreg on the lower panel according to its size on the tooling. Use the tooling to vertically position and secure the cured and trimmed bridge web foot to the uncured lower panel. Place adhesive film on the contact surface. Bag the assembled parts, evacuate them, and place them in an autoclave for curing. Demolding and trimming are then completed.

[0020] Step 4: Integral bonding: Use high-temperature adhesive to bond and cure the top plane of the cured bridge web to the upper panel;

[0021] Step 5: Demolding and trimming: Demold the cured composite product and polish and trim it.

[0022] The curing process of the bridge-type web is to cure the quartz fiber / phenolic prepreg, the glass fiber / phenolic prepreg and the carbon fiber / high-temperature epoxy prepreg under the same curing system. The curing system is: first, keep warm at 90°C to 110°C for 1 to 3 hours, then keep warm at 120°C to 140°C for 2 to 5 hours, and finally keep warm at 150°C to 170°C for 3 to 4 hours. The curing pressure is 0.16 to 0.8 MPa.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The bridge-type web adopts a combination of ablation resistance, thermal insulation and load-bearing, and the material is set to a multi-layer gradient composite structure. The outer layer has the lowest thermal conductivity and is ablation-resistant, the middle layer has low thermal conductivity and lower density than the outer layer, and the innermost layer has the lowest density and excellent mechanical properties. The three-layer structure of the web is composed of continuously changing component materials, which increases the reduction effect of heat transfer at each interface and reduces the thermal short-circuit problem common in thermal insulation corrugated panels. The layer thickness and position distribution of different layers can be adjusted according to the use environment to meet the extreme working environment of aerospace vehicles.

[0025] 2. A bridge-type web structure with decreasing thickness is adopted. The bottom carbon fiber structural layer is responsible for the load-bearing function. The thickness of the ablation-resistant, heat-insulating, and load-bearing layers is rationally planned to maximize the reduction of the web mass while meeting the requirements of thermal protection and load-bearing capacity.

[0026] 3. The web of the bridge structure is used as the load-bearing structure of this product, which has the advantages of stable structure, strong load-bearing capacity and firm connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 Schematic diagram of the overall structure of the multi-gradient heat-resistant and load-bearing integrated composite material of the present invention;

[0029] Figure 2 Schematic diagram of the bridge-type web structure of the multi-gradient heat-resistant and load-bearing integrated composite material of the present invention;

[0030] Figure 3 It is a schematic plan view of the bridge-shaped web of the multi-gradient heat-resistant and load-bearing integrated composite material of the present invention;

[0031] Figure 4 Schematic diagram of the bonding structure of the upper panel of the multi-gradient heat-resistant and load-bearing integrated composite material of the present invention;

[0032] In the figure, 100 is the upper panel; 200 is the bridge-type web; 300 is the sandwich insulation material; 400 is the lower panel; 101 is the bonding structural surface of the upper panel; 201 is the ablation-resistant structural layer; 202 is the thermal insulation structural layer; 203 is the load-bearing structural layer, and 204 is the top bonding structural surface. DETAILED DESCRIPTION

[0033] The present invention is further described below with reference to the accompanying drawings and specific embodiments. However, it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various modifications, substitutions and changes made according to common technical knowledge and customary means in the field are included in the scope of the present invention.

[0034] Reference Figure 1-Figure 4 A multi-gradient heat-resistant and load-bearing integrated composite material, consisting of an upper panel 100, a bridge-shaped web 200, a sandwich insulation material 300, and a lower panel 400. The upper plane of the bridge-shaped web 200 is connected to the upper panel 100 through a secondary bonding process. The sandwich insulation material 300 is filled in the gaps between the upper panel 100, the bridge-shaped web 200, and the lower panel 100. The bottom plane of the bridge-shaped web 200 is vertically connected to the lower panel 100 through a co-curing bonding process.

[0035] The bridge-type web 200 is a multi-gradient composite bridge structure, which is formed by paving an ablation-resistant structural layer 201, a thermal insulation structural layer 202, and a load-bearing structural layer 203 from top to bottom using prepreg. The ablation-resistant structural layer 201 and the thermal insulation structural layer 202 are distributed in a gradually decreasing structure from top to bottom. The bottom end of the ablation-resistant structural layer 201 is paved on the thermal insulation structural layer 202, and the bottom end of the thermal insulation structural layer 202 is paved on the load-bearing structural layer 203. The end of the load-bearing structural layer 203 is in contact with the lower panel 100 at a 90-degree angle.

[0036] The bridge-shaped web 200 is provided with a 180° top bonding structural surface, and the area of ​​the top bonding structural surface accounts for 5% to 9% of the upper surface area of ​​the bridge-shaped web 200 .

[0037] Taking the overall height of the bridge-type web 200 as a reference plane, the height of the ablation-resistant structural layer 201 is 60% to 70% of the height of the bridge-type web 200, and the thickness decreases from the top layer to both sides of the ablation-resistant structural layer 201, and decreases from the maximum thickness of the layer to 0 mm; the height of the thermal insulation structural layer 202 is 70% to 90% of the height of the bridge-type web 200, and the thickness decreases from the top layer to both sides of the thermal insulation structural layer 202, and decreases from the maximum thickness of the layer to 0 mm; the thickness of the load-bearing structural layer 203 remains unchanged from top to bottom.

[0038] The maximum thickness of the bridge-type web 200 is 1.5 to 3.8 mm, wherein the ablation-resistant structural layer 201 is made of quartz / phenolic prepreg, and the maximum thickness of the layer is 0.2 to 1 mm; the thermal insulation structural layer 202 is made of glass fiber / phenolic prepreg, and the maximum thickness of the layer is 0.3 to 0.8 mm; the load-bearing structural layer 203 is made of carbon fiber / high-temperature epoxy prepreg, and the thickness of the layer is 1 to 2 mm.

[0039] The upper panel 100 is formed by paving and curing quartz fiber / phenolic prepreg, and the thickness of the panel is 1.5-4 mm.

[0040] The lower panel 400 is made of carbon fiber / high temperature epoxy prepreg laid and cured, and the panel thickness is 1 to 3 mm.

[0041] The high-temperature epoxy resin matrix and the phenolic resin matrix in the carbon fiber / high-temperature epoxy prepreg, the quartz fiber / phenolic prepreg and the glass fiber / phenolic prepreg have similar glass transition temperatures.

[0042] The core insulation material 300 is made of one or more combinations of alumina fiber insulation material, ultrafine glass fiber material, and silica aerogel insulation felt.

[0043] A method for preparing a multi-gradient heat-resistant and load-bearing integrated composite material comprises the following steps:

[0044] Step 1: Preparation of the bridge-shaped web 200: The steps are as follows: mold preparation, prepreg preparation, mold release application, prepreg cutting, laying of bottom carbon fiber / high-temperature epoxy prepreg, vacuum pre-compaction, laying of glass fiber / phenolic prepreg, hot compaction, laying of top quartz fiber / phenolic prepreg, hot compaction, bagging and vacuuming, curing, demoulding, trimming, and polishing.

[0045] Step 2: Prepare the upper panel 100: The upper panel 100 is formed into a flat plate with the required dimensions by using a paving-autoclave molding process;

[0046] Step 3: Prepare the lower panel 400 and bond it to the bridge-shaped web 200: Pre-compact the carbon fiber prepreg on the lower panel 400 according to its size on the tooling. Use the tooling to vertically position and secure the cured and trimmed bridge-shaped web 200 to the uncured lower panel 400. Place adhesive film on the contact surface. Bag the assembled parts, evacuate them, place them in an autoclave for curing, and complete demoulding and trimming.

[0047] Step 4: Overall bonding: Place the lower panel 400 and the bridge-shaped web 200 after demolding and modification, and use high-temperature adhesive to apply to the bonding structural surface 101 of the upper panel 100 and the top bonding structural surface 204 of the bridge-shaped web 200. Then assemble them so that the top plane of the bridge-shaped web 20 and the upper panel 100 are bonded and cured.

[0048] Step 5: Demolding and trimming: Demold the cured composite product and polish and trim it.

[0049] The curing process of the bridge-type web 200 is to cure the quartz fiber / phenolic prepreg, glass fiber / phenolic prepreg and carbon fiber / high-temperature epoxy prepreg under the same curing system. The curing system is: first, keep it at 90℃~110℃ for 1~3 hours, then keep it at 120℃~140℃ for 2~5 hours, and finally keep it at 150℃~170℃ for 3~4 hours. The curing pressure is 0.16~0.8MPa.

[0050] The above is a detailed introduction to a multi-gradient heat-resistant and load-bearing integrated composite material and its preparation method provided by the present invention. Specific examples are used herein to illustrate the structure and working principle of the present invention. The description of the above embodiments is only used to help understand the method and core concept of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A multi-gradient heat-resistant and load-bearing integrated composite material, comprising an upper panel (100), a bridge-shaped web (200), a sandwich insulation material (300), and a lower panel (400), characterized in that: The upper plane of the bridge-shaped web (200) is connected to the upper panel (100) through a secondary bonding process, and the bottom plane of the bridge-shaped web (200) is vertically connected to the lower panel (400) through a bonding co-curing process; The bridge-type web (200) is a multi-gradient composite bridge structure, which is formed by paving a preformed body from top to bottom with a prepreg material using an ablation-resistant structural layer (201), a thermal insulation structural layer (202) and a load-bearing structural layer (203). The ablation-resistant structural layer (201) and the thermal insulation structural layer (202) are distributed in a gradually decreasing structure from top to bottom. Taking the overall height of the bridge-type web (200) as a reference surface, the height of the ablation-resistant structural layer (201) is 60% to 70% of the height of the bridge-type web (200), and the thickness decreases from the top layer of the ablation-resistant structural layer (201) to both sides, and decreases from the maximum thickness of the ply to 0 mm; the height of the thermal insulation structural layer (202) is 70% to 90% of the height of the bridge-type web (200), and the thickness decreases from the top layer of the thermal insulation structural layer (202) to both sides, and decreases from the maximum thickness of the ply to 0 mm; the thickness of the load-bearing structural layer (203) remains unchanged from top to bottom; The ablation-resistant structural layer (201) is formed by paving quartz fiber / phenolic prepreg, the heat-insulating structural layer (202) is formed by paving glass fiber / phenolic prepreg, and the load-bearing structural layer (203) is formed by paving carbon fiber / high-temperature epoxy prepreg; The bottom end of the ablation-resistant structural layer (201) is laid on the thermal insulation structural layer (202), and the bottom end of the thermal insulation structural layer (202) is laid on the load-bearing structural layer (203). The end of the load-bearing structural layer (203) is in contact with the lower panel (400) at a 90-degree angle. The bridge-shaped web (200) is provided with a 180-degree top bonding structural surface, and the area of ​​the top bonding structural surface accounts for 5% to 9% of the upper surface area of ​​the bridge-shaped web (200).

2. The multi-gradient heat-resistant and load-bearing integrated composite material according to claim 1, characterized in that: The maximum thickness of the bridge-shaped web (200) is 1.5-3.8 mm, wherein the maximum thickness of the ablation-resistant structural layer (201) is 0.2-1 mm; the maximum thickness of the thermal insulation structural layer (202) is 0.3-0.8 mm; and the thickness of the load-bearing structural layer (203) is 1-2 mm.

3. The multi-gradient heat-resistant and load-bearing integrated composite material according to claim 1, characterized in that: The upper panel (100) is formed by paving and curing quartz fiber / phenolic prepreg, and the thickness of the upper panel is 1.5-4 mm.

4. The multi-gradient heat-resistant and load-bearing integrated composite material according to claim 1, characterized in that: The lower panel (400) is formed by paving and curing carbon fiber / high-temperature epoxy prepreg, and the thickness of the lower panel is 1-3 mm.

5. The multi-gradient heat-resistant and load-bearing integrated composite material according to claim 1, characterized in that: The high-temperature epoxy resin matrix and the phenolic resin matrix in the carbon fiber / high-temperature epoxy prepreg, the quartz fiber / phenolic prepreg and the glass fiber / phenolic prepreg have similar glass transition temperatures.

6. The multi-gradient heat-resistant and load-bearing integrated composite material according to claim 1, characterized in that: The sandwich insulation material (300) is filled in the gaps between the upper panel (100), the bridge-shaped web (200) and the lower panel (400), and the material of the sandwich insulation material (300) is one or more combinations of alumina fiber insulation material, ultrafine glass fiber material, and silica aerogel insulation felt.

7. A method for preparing a multi-gradient thermal protection and load-bearing integrated composite material, for preparing the multi-gradient thermal protection and load-bearing integrated composite material according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: preparing the bridge-shaped web (200): preparing a mold, preparing prepreg, applying a release agent, cutting the prepreg, laying the bottom carbon fiber / high-temperature epoxy prepreg, vacuum pre-compacting, laying the glass fiber / phenolic prepreg, hot compacting, laying the top quartz fiber / phenolic prepreg, hot compacting, bagging and vacuuming, curing, demoulding, trimming, and polishing; Step 2: preparing the upper panel (100): the upper panel (100) is formed into a plane plate having a desired size by using a paving-autoclave forming process; Step 3: Prepare the lower panel (400) and bond it to the bridge-shaped web (200): pre-compact the carbon fiber prepreg on the tooling according to the size to obtain the uncured lower panel (400); use the tooling to vertically place the foot of the bridge-shaped web (200) prepared in step 1 and fix it on the uncured lower panel (400), and place a film on the contact surface. The assembled parts are bagged and vacuumed, placed in an autoclave for curing, and demoulding and trimming are completed; Step 4: Integral bonding: Use a high-temperature adhesive to bond and cure the top plane of the cured bridge-shaped web (200) to the upper panel (100); Step 5: Demolding and trimming: Demold the cured composite product and polish and trim it.

8. The method for preparing the multi-gradient heat-resistant and load-bearing integrated composite material according to claim 7, characterized in that: The curing process of the bridge-type web (200) is to cure the quartz fiber / phenolic prepreg, the glass fiber / phenolic prepreg and the carbon fiber / high-temperature epoxy prepreg under the same curing system. The curing system is: first, keep warm at 90°C to 110°C for 1 to 3 hours, then keep warm at 120°C to 140°C for 2 to 5 hours, and finally keep warm at 150°C to 170°C for 3 to 4 hours, and the curing pressure is 0.16~0.8MPa.

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