Gradient density phenolic resin-based air rudder, its preparation mold and preparation method

Abstract

The present invention relates to the technical field of preparation of resin-based thermal protection materials, and in particular to a gradient density phenolic resin-based air rudder, a preparation mold and a preparation method thereof. The preparation method comprises selecting a metal rudder core, preparing a first female mold component and a second female mold component; wrapping a low-density high-silica fiber felt calcined at high temperature on the outer surface of the metal rudder core, fixing the metal rudder core in the inner cavity of the first female mold and pouring low-density phenolic resin, performing a first curing and molding, demoulding, and obtaining a metal rudder core with a low-density thermal insulation layer; wrapping a 2.5D woven high-density carbon fiber preform that has undergone an antioxidant treatment on the outer surface of the low-density thermal insulation layer, fixing the metal rudder core in the inner cavity of the second female mold and pouring high-density phenolic resin, performing a second curing and molding, demoulding, and machining to obtain a high-density anti-ablation layer, thereby preparing a gradient density phenolic resin-based air rudder; the air rudder obtained by the present invention has low cost, good anti-ablation performance and excellent thermal insulation performance.

Description

Technical Field

[0001] The invention relates to the technical field of heat-resistant composite materials, and in particular to a gradient-density phenolic resin-based air rudder, a mold for preparing the same, and a preparation method thereof. Background Art

[0002] Thermal protection technology is an important means to protect devices from thermal damage and is widely used in the aerospace field. Thermal protection materials are the key materials of this technology. When a spacecraft flies at hypersonic speeds, the operating conditions of the air rudder are the most demanding. The temperature of the rudder surface will reach over 2000℃, and the temperature of the rudder leading edge will reach over 2500℃. Therefore, extremely high requirements are placed on the heat protection materials of the air rudder.

[0003] At present, in order to prepare ultra-high temperature and long-endurance aircraft air rudder products for use in the aerospace field, carbon fiber reinforced silicon carbide ceramic-based composite materials are mainly used. This material adopts the precursor impregnation pyrolysis process (PIP) or chemical vapor infiltration process (CVI), which has a long production cycle, high manufacturing cost, and high product price, and it is difficult to meet the requirements of future models for low-cost design and manufacturing; and the high-density phenolic resin-based composite materials with uniform structure have high comprehensive thermal conductivity. Under ultra-high temperature and long-endurance flight conditions, the surface temperature of the metal rudder core is significantly higher than its tolerance temperature, which is difficult to meet the design requirements.

[0004] The functional structure of gradient design materials has significant advantages: first, the excellent anti-ablation performance gives the material good dimensional ability and aerodynamic stability; second, the excellent thermal insulation performance can reduce the design thickness of heat protection products and reduce negative mass; third, it can achieve multifunctional integrated design such as anti-ablation, thermal insulation, and load-bearing; therefore, it plays an extremely important role in the preparation of long-endurance air rudders in ultra-high temperature environments.

[0005] Therefore, in order to solve the above problems, the present invention urgently needs to provide a gradient density phenolic resin-based air rudder, a preparation mold and a preparation method thereof. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide a gradient density phenolic resin-based air rudder, a preparation mold and a preparation method thereof. By performing a layered design on the air rudder, a low-density high-silica fiber felt calcined at high temperature is used as a low-density thermal insulation layer reinforcement, and a 2.5D contoured woven high-density carbon fiber preform after antioxidant treatment is used as a high-density anti-ablation layer reinforcement, a low-cost, ultra-density gradient density phenolic resin-based composite material air rudder is prepared by secondary RTM infusion molding, which significantly improves the thermal insulation performance of the material while maintaining the good anti-ablation performance of the material, meeting the structural heat protection integrated design requirements and cost control needs of long-endurance air rudders in ultra-high temperature environments.

[0007] The present invention provides a method for preparing a gradient density phenolic resin-based air rudder, comprising the following steps:

[0008] 1) preparing a first female mold assembly having a first female mold cavity and a second female mold assembly having a second female mold cavity; wherein the cross-sectional area of ​​the first female mold cavity is smaller than the cross-sectional area of ​​the second female mold cavity;

[0009] 2) selecting a low-density high-silica fiber felt, calcining it at a high temperature, and wrapping the calcined low-density high-silica fiber felt around the outer surface of the metal rudder core to obtain a first preform;

[0010] 3) Fixing the first prefabricated component in the inner cavity of the first female mold, pouring low-density phenolic resin into the inner cavity of the first female mold, curing and molding it for the first time, and demolding to obtain a metal rudder core coated with a low-density thermal insulation layer;

[0011] 4) wrapping the high-density carbon fiber preform after the antioxidant treatment around the low-density thermal insulation layer to obtain a second preform;

[0012] 5) Fixing the second preform in the inner cavity of the second female mold, pouring high-density phenolic resin into the inner cavity of the second female mold, curing and molding for the second time, demolding, machining, forming a high-density anti-ablation layer outside the low-density thermal insulation layer, and obtaining a gradient density phenolic resin-based air rudder.

[0013] Preferably, in step 2), the high temperature calcination process is to raise the temperature to 600-800°C and keep the temperature for 30-90 minutes. The density of the low-density high-silica fiber felt after calcination is 0.18-0.23 g / cm 3 .

[0014] Preferably, in step 3), the low-density phenolic resin is a LP series phenolic resin produced by North Glass Institute, with a solid content of 30-50% and a density of 0.95-1.05 g / cm 3 The viscosity is less than 50mPa·s, and the density of the phenolic resin matrix after curing is 0.35~0.45g / cm 3 .

[0015] Preferably, in step 3), the injection pressure of the low-density phenolic resin into the inner cavity of the first female mold is 0.3-0.5 MPa; the first curing molding process is to heat the material to 80-100°C at a heating rate of 10°C / min and keep it warm for 12-36 hours; after curing is completed, dry it at 40-60°C for 12-24 hours, and then heat it to 80-100°C and dry it for 12-24 hours.

[0016] Preferably, in step 4), the density of the high-density carbon fiber preform is 0.75 to 0.95 g / cm 3The anti-oxidation treatment process includes the following steps: immersing the high-density carbon fiber preform in a 10-15wt% polycarbosilane / xylene solution for 3-5 hours, drying the preform, and coating the surface with a polycarbosilane anti-oxidation layer; wherein the residual weight of the polycarbosilane after pyrolysis at 800°C is greater than 70%.

[0017] Preferably, in step 5), the high-density phenolic resin is a RTM series phenolic resin produced by North Glass Research Institute, with a solid content of 85-90% and a density of 1.05-1.15 g / cm 3 The viscosity is 800-1000 mPa·s, and the density of the phenolic resin matrix after curing is 1.15-1.25 g / cm 3 .

[0018] Preferably, in step 5), before pouring high-density phenolic resin into the inner cavity of the second female mold, the inner cavity of the second female mold is first evacuated to below -0.1 MPa. During pouring, the high-density phenolic resin tank is auxiliary pressurized with 1 to 3 MPa; the second curing molding process is to heat the temperature to 180 to 200°C at a heating rate of 10°C / min and keep warm for 12 to 24 hours; and naturally cool after curing is completed.

[0019] The present invention also provides a gradient density phenolic resin-based air rudder obtained by the above-mentioned preparation method of the gradient density phenolic resin-based air rudder, comprising a metal rudder core, the metal rudder core being sequentially coated with a low-density heat insulation layer and a high-density anti-ablation layer;

[0020] Among them, the low-density thermal insulation layer is obtained by curing low-density high-silica fiber felt calcined at high temperature with low-density phenolic resin through RTM process, and the high-density anti-ablation layer is obtained by curing high-density carbon fiber preform after antioxidant treatment with high-density phenolic resin through RTM process.

[0021] The present invention also provides a mold assembly for preparing the gradient density phenolic resin-based air rudder as described above, comprising a metal rudder core, a first female mold assembly, and a second female mold assembly;

[0022] The upper surface of the metal rudder core is further provided with a rudder shaft extending upward for positioning with the first female mold assembly and the second female mold assembly;

[0023] The first female mold assembly includes a first upper cover plate, a first left cover plate, a first right cover plate, and a first front cover plate; a first molding groove is provided on the lower surface of the first upper cover plate, a second molding groove is provided on the right side surface of the first left cover plate, a third molding groove is provided on the left side surface of the first right cover plate, and a fourth molding groove is provided on the rear side surface of the first front cover plate. The first molding groove, the second molding groove, the third molding groove, and the fourth molding groove are all arranged in accordance with the shape of the metal rudder core, and a first molding gap is formed between the first molding groove, the second molding groove, the third molding groove, the fourth molding groove and the metal rudder core; a first positioning hole matching the rudder shaft is also provided through the upper surface of the first upper cover plate;

[0024] The second female mold assembly includes a second upper cover plate, a second left cover plate, a second right cover plate, and a second front cover plate; a fifth molding groove is provided on the lower surface of the second upper cover plate, a sixth molding groove is provided on the right side surface of the second left cover plate, a seventh molding groove is provided on the left side surface of the second right cover plate, and an eighth molding groove is provided on the rear side surface of the second front cover plate; a second molding gap is formed between the fifth molding groove, the sixth molding groove, the seventh molding groove, and the eighth molding groove and the metal rudder core; a second positioning hole is also provided through the upper surface of the second upper cover plate to match the rudder shaft;

[0025] The width of the second molding gap is greater than the width of the first molding gap.

[0026] Preferably, the side surface of the rudder shaft is further provided with a fixing socket for positioning the angle of the metal rudder core, and the root of the rudder shaft is further provided with an annular boss.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides a gradient density phenolic resin-based air rudder, a preparation mold and a preparation method thereof. The air rudder is designed in layers, a low-density high-silica fiber felt calcined at high temperature is cured with a low-density phenolic resin RTM process to prepare a low-density thermal insulation layer, a high-density carbon fiber preform after antioxidant treatment is cured with a high-density phenolic resin RTM process to prepare a high-density anti-ablation layer, and a gradient density phenolic resin-based composite material air rudder is prepared by secondary RTM process curing and molding. Compared with the existing high-density phenolic resin-based composite material air rudder with uniform structure, the air rudder material obtained by the present invention has lower comprehensive density and significantly improved thermal insulation performance, while maintaining good anti-ablation performance of the material, and can meet the design requirements of phenolic resin-based composite material air rudders for long-endurance aircraft in ultra-high temperature environments; at the same time, the main raw materials of the present invention can be obtained from diversified market supplies, which can significantly reduce costs, and can further shorten the preparation cycle on the premise that the fiber preform is prepared in advance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1is a flow chart of a method for preparing a gradient density phenolic resin-based air rudder according to an embodiment of the present invention;

[0030] Figure 2 1 is a structural schematic diagram (exploded view) of the first female mold assembly according to an embodiment of the present invention;

[0031] Figure 3 is an exploded view of the first female mold assembly from another angle according to an embodiment of the present invention;

[0032] Figure 4 Schematic diagram (exploded view) of the structure of the second female mold assembly according to an embodiment of the present invention;

[0033] Figure 5 An exploded view of the second female mold assembly from another angle according to an embodiment of the present invention;

[0034] Figure 6 2 is a schematic structural diagram (cross-sectional view) of a gradient density phenolic resin-based air rudder according to an embodiment of the present invention.

[0035] Among them: 1. Metal rudder core; 101. Rudder shaft; 102. Annular boss; 103. Fixing socket; 3. Low-density thermal insulation layer; 4. High-density anti-ablation layer; 501. First upper cover plate; 5011. First molding groove; 5012. First positioning hole; 502. First left cover plate; 5021. Second molding groove; 503. First right cover plate; 5031. Third molding groove; 504. First front cover plate; 5041. Fourth molding groove; 601. Second upper cover plate; 6011. Fifth molding groove; 6012. Second positioning hole; 602. Second left cover plate; 6021. Sixth molding groove; 603. Second right cover plate; 6031. Seventh molding groove; 604. Second front cover plate; 6041. Eighth molding groove. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] like Figure 1 As shown, the present invention provides a method for preparing a gradient density phenolic resin-based air rudder, comprising the following steps:

[0038] 1) preparing a first female mold assembly having a first female mold cavity and a second female mold assembly having a second female mold cavity; wherein the cross-sectional area of ​​the first female mold cavity is smaller than the cross-sectional area of ​​the second female mold cavity;

[0039] 2) Selecting a metal rudder core 1, selecting a low-density high-silica fiber felt, calcining it at high temperature, and wrapping the calcined low-density high-silica fiber felt around the outer surface of the metal rudder core 1 to obtain a first preform;

[0040] 3) Fixing the first prefabricated component in the inner cavity of the first female mold, pouring low-density phenolic resin into the inner cavity of the first female mold, curing and molding for the first time, and demoulding to obtain the metal rudder core 1 coated with the low-density heat insulation layer 3;

[0041] 4) Select carbon fibers and perform high-density contour weaving using a 2.5D weaving method to obtain a high-density carbon fiber preform. The high-density carbon fiber preform after antioxidant treatment is conformally coated on the low-density thermal insulation layer 3 to obtain a second preform;

[0042] 5) Fix the second preform in the inner cavity of the second female mold, pour high-density phenolic resin into the inner cavity of the second female mold, solidify and shape it for the second time, demould, and machine it to form a high-density anti-ablation layer 4 outside the low-density thermal insulation layer 3 to obtain a gradient density phenolic resin-based air rudder.

[0043] The present invention provides a method for preparing a gradient density phenolic resin-based air rudder, which comprises the following steps: performing a layered design on the air rudder, curing a low-density thermal insulation layer 3 using a low-density high-silica fiber felt calcined at high temperature and a low-density phenolic resin through an RTM process, curing a high-density anti-ablation layer 4 using a high-density carbon fiber preform after antioxidant treatment and a high-density phenolic resin through an RTM process, and preparing a gradient density phenolic resin-based composite air rudder through a secondary RTM infusion curing molding method. Compared with the existing high-density phenolic resin-based composite air rudder with uniform structure, the air rudder material obtained by the present invention has lower comprehensive density and significantly improved thermal insulation performance, while maintaining good anti-ablation performance of the material, and can meet the design requirements of phenolic resin-based composite air rudders for long-endurance aircraft in ultra-high temperature environments; at the same time, the main raw materials of the present invention can be obtained from a diversified market supply, which can significantly reduce costs, and can further shorten the preparation cycle on the premise that the fiber preform is prepared in advance.

[0044] In the embodiments of the present invention, the main raw materials used can be obtained from a variety of market supplies; for existing ceramic-based composite materials, polycarbosilane is selected as the raw material, and its market price is about 4,000 to 5,000 yuan / kg, and the price of the ceramic-based composite air rudder is about 40,000 to 60,000 yuan / kg; and for the gradient density phenolic resin-based air rudder described in the present invention, the market price of low-density high-silica fiber felt is 80 to 150 yuan / kg, the market price of carbon fiber is 200 to 300 yuan / kg, the cost of low-density LP series phenolic resin is 400 to 500 yuan / kg, and the cost of high-density RTM series phenolic resin is 100 to 200 yuan / kg. The resulting gradient density phenolic resin-based air rudder can control its selling price at 8,000 to 10,000 yuan / kg, and the product price advantage is outstanding.

[0045] For the existing high-density phenolic resin-based composite air rudder with uniform structure, its comprehensive density is greater than 1.6g / cm 3 , the comprehensive thermal conductivity is 0.3-0.45W / m·K; and for the gradient density phenolic resin-based air rudder of the present invention, the comprehensive density of the material is about 0.65-0.75g / cm 3 The thermal conductivity of the thermal insulation layer is less than 0.1W / m·K, the thermal conductivity of the anti-ablation layer is 0.35~0.5W / m·K, and the comprehensive thermal conductivity is less than 0.2W / m·K; therefore, the air rudder product prepared by the present invention has a lower comprehensive density, better comprehensive anti-ablation and thermal insulation performance, and lower manufacturing cost, which can meet the high-performance and low-cost preparation requirements of air rudders for long-endurance aircraft in ultra-high temperature environments.

[0046] The existing carbon fiber reinforced silicon carbide ceramic matrix composite air rudder has a preparation cycle of about 45 to 60 days, provided that the preform is ready. However, the present invention has a production cycle of about 15 to 20 days, provided that the low-density high-silica fiber felt after high-temperature calcination and the high-density carbon fiber preform after oxidation treatment are ready. Therefore, the preparation cycle of the present invention is significantly shortened, the overall cost-effectiveness is significantly improved, and the competitive advantage is stronger.

[0047] In the present invention, the density of the low-density heat-insulating layer 3 is 0.45 to 0.65 g / cm 3 , the thermal conductivity is less than 0.1W / m·K; the density of the high-density anti-ablation layer 4 is 1.5-1.65g / cm 3 , thermal conductivity is less than 0.5W / m·K, and oxyacetylene wire ablation rate is less than 0.05mm / s.

[0048] In this embodiment, in step 2), the high temperature calcination process is to raise the temperature to 600-800°C and keep the temperature for 30-90 minutes. The density of the high silica fiber felt reinforcement after calcination is 0.18-0.23 g / cm 3 .

[0049] In this embodiment, in step 3), the low-density phenolic resin is the LP series phenolic resin produced by North Glass Institute, with a solid content of 30-50% and a density of 0.95-1.05 g / cm 3 , viscosity is less than 50mPa·s; the density of the phenolic resin matrix formed after curing is 0.35~0.45g / cm 3 .

[0050] In this embodiment, in step 3), the low-density phenolic resin is injected into the first female mold cavity with an injection pressure of 0.3 to 0.5 MPa. After injection, the binder and air are repeatedly discharged for 3 to 5 times until there are no bubbles in the discharge pipe. The first curing molding process is to heat the temperature to 80 to 100°C at a heating rate of 10°C / min and keep it warm for 12 to 36 hours. After the curing is completed, it is dried at 40 to 60°C for 12 to 24 hours, and then heated to 80 to 100°C and dried for 12 to 24 hours.

[0051] In this embodiment, in step 4), the density of the high-density carbon fiber preform is 0.75-0.95 g / cm 3 The anti-oxidation treatment process includes the following steps: immersing a high-density carbon fiber preform in a 10-15wt% polycarbosilane / xylene solution for 3-5 hours, drying, and coating the surface with a polycarbosilane anti-oxidation layer; wherein the residual weight of polycarbosilane after cracking at 800°C is greater than 70%, that is, the ratio of the residual weight of polycarbosilane after cracking at 800°C under nitrogen protection conditions to the weight before cracking is greater than 70%.

[0052] In this embodiment, in step 5), the high-density phenolic resin is a RTM series phenolic resin produced by North Glass Research Institute, with a solid content of 85-90% and a density of 1.05-1.15 g / cm 3 , viscosity is 800-1000 mPa·s; density of the phenolic resin matrix formed after curing is 1.15-1.25 g / cm 3 .

[0053] In this embodiment, in step 5), the perfusion process of injecting high-density phenolic resin into the second female mold cavity is as follows: first, the second female mold cavity is vacuumed to below -0.1MPa, and during perfusion, the high-density phenolic resin tank is auxiliary pressurized with 1~3MPa. After perfusion, the binder and air are repeatedly discharged and exhausted 3~5 times until there are no bubbles in the discharge hose; the second curing molding process is to heat the temperature to 180~200℃ at a heating rate of 10℃ / min and keep warm for 12~24h; and naturally cool after curing is completed.

[0054] like Figure 6As shown, the present invention provides a gradient density phenolic resin-based air rudder obtained based on the preparation method of the gradient density phenolic resin-based air rudder as described above, comprising a metal rudder core 1, the metal rudder core 1 being sequentially coated with a low-density heat insulation layer 3 and a high-density anti-ablation layer 4;

[0055] Among them, the low-density thermal insulation layer 3 is obtained by curing low-density high-silica fiber felt calcined at high temperature with low-density phenolic resin through RTM process, and the high-density anti-ablation layer 4 is obtained by curing high-density carbon fiber preform after antioxidant treatment with high-density phenolic resin through RTM process.

[0056] The present invention provides a gradient density phenolic resin-based air rudder. The air rudder is designed in layers, and a low-density heat-insulating layer 3 is obtained by curing a low-density high-silica fiber felt calcined at high temperature with a low-density phenolic resin through an RTM process. A high-density anti-ablation layer 4 is obtained by curing a high-density carbon fiber preform after antioxidant treatment with a high-density phenolic resin through an RTM process. The gradient density phenolic resin-based composite material air rudder is prepared by secondary RTM infusion curing molding. Compared with the existing high-density phenolic resin-based composite material air rudder with uniform structure, the air rudder material obtained by the present invention has lower comprehensive density and significantly improved heat insulation performance, while maintaining good anti-ablation performance of the material, and can meet the design requirements of the phenolic resin-based composite material air rudder for long-endurance aircraft in ultra-high temperature environments. At the same time, the main raw materials of the present invention can be obtained from a diversified market supply, which can significantly reduce costs, and can further shorten the preparation cycle on the premise that the fiber preform is prepared in advance.

[0057] like Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 As shown, the present invention provides a mold assembly for preparing a gradient density phenolic resin-based air rudder, comprising a metal rudder core 1, a first female mold assembly and a second female mold assembly;

[0058] The upper surface of the metal rudder core 1 is further provided with a rudder shaft 101 extending upwards for positioning with the first female mold assembly and the second female mold assembly;

[0059] The first female mold assembly includes a first upper cover plate 501, a first left cover plate 502, a first right cover plate 503 and a first front cover plate 504; a first molding groove 5011 is provided on the lower surface of the first upper cover plate 501, a second molding groove 5021 is provided on the right side surface of the first left cover plate 502, a third molding groove 5031 is provided on the left side surface of the first right cover plate 503, and a fourth molding groove 5041 is provided on the rear side surface of the first front cover plate 504. The first molding groove 5011, the second molding groove 5021, the third molding groove 5031 and the fourth molding groove 5041 are all arranged in accordance with the shape of the metal rudder core 1, and a first molding gap is formed between the first molding groove 5011, the second molding groove 5021, the third molding groove 5031 and the fourth molding groove 5041 and the metal rudder core 1; a first positioning hole 5012 is also provided on the upper surface of the first upper cover plate 501 to match the rudder shaft 101;

[0060] The second female mold assembly includes a second upper cover plate 601, a second left cover plate 602, a second right cover plate 603, and a second front cover plate 604. A fifth molding groove 6011 is provided on the lower surface of the second upper cover plate 601, a sixth molding groove 6021 is provided on the right side surface of the second left cover plate 602, a seventh molding groove 6031 is provided on the left side surface of the second right cover plate 603, and an eighth molding groove 6041 is provided on the rear side surface of the second front cover plate 604. A second molding gap is formed between the fifth molding groove 6011, the sixth molding groove 6021, the seventh molding groove 6031, and the eighth molding groove 6041 and the metal rudder core 1. A second positioning hole 6012 is also provided on the upper surface of the second upper cover plate 601 to match the rudder shaft 101.

[0061] The width of the second molding gap is greater than the width of the first molding gap.

[0062] In this embodiment, a first glue inlet is provided at the bottom end of the inner mold surface of the first female mold component, and a first glue outlet is provided at the top end. The pressure resistance of the molding cavity of the first female mold component is greater than 2MPa; a second glue inlet is provided at the bottom end of the inner mold surface of the second female mold component, and a second glue outlet is provided at the top end. The pressure resistance of the molding cavity of the second female mold component is greater than 12MPa.

[0063] In the present invention, the metal rudder core 1 is made of titanium alloy.

[0064] The present invention provides a mold for preparing a gradient density phenolic resin-based air rudder. The air rudder is designed in layers, and a low-density high-silica fiber felt calcined at high temperature is used with a low-density phenolic resin to be cured through an RTM process to obtain a low-density thermal insulation layer 3. A high-density carbon fiber preform after antioxidant treatment is used with a high-density phenolic resin to be cured through an RTM process to obtain a high-density anti-ablation layer 4. A gradient density phenolic resin-based composite air rudder is prepared by secondary RTM infusion curing molding. Compared with the existing high-density phenolic resin-based composite air rudder with uniform structure, the air rudder material obtained by the present invention has lower comprehensive density and significantly improved thermal insulation performance, while maintaining good anti-ablation performance of the material, and can meet the design requirements of phenolic resin-based composite air rudders for long-endurance aircraft in ultra-high temperature environments. At the same time, the main raw materials of the present invention can be obtained from a diversified market supply, which can significantly reduce costs, and can further shorten the preparation cycle on the premise that the fiber preform is prepared in advance.

[0065] In this embodiment, a fixing hole 103 for positioning the angle of the metal rudder core 1 is further provided on the side surface of the rudder shaft 101 , and an annular boss 102 is further provided at the root of the rudder shaft 101 .

[0066] In the present invention, the first upper cover 501 and the first left cover 502, the first upper cover 501 and the first right cover 503, the first left cover 502 and the first right cover 503, the first front cover 504 and the first upper cover 501, the first front cover 504 and the first left cover 502, and the first front cover 504 and the first right cover 503 are all fixed by first positioning members;

[0067] The second upper cover 601 and the second left cover 602, the second upper cover 601 and the second right cover 603, the second left cover 602 and the second right cover 603, the second front cover 604 and the second upper cover 601, the second front cover 604 and the second left cover 602, and the second front cover 604 and the second right cover 603 are all fixed by second positioning members;

[0068] Wherein, the first positioning member and the second positioning member are both positioning pins or bolts.

[0069] The present invention also provides an embodiment of a method for preparing a gradient density phenolic resin-based air rudder, comprising the following steps:

[0070] 1) Selecting a metal rudder core 1, preparing a first female mold assembly having a first female mold cavity and a second female mold assembly having a second female mold cavity; wherein the cross-sectional area of ​​the first female mold cavity is smaller than the cross-sectional area of ​​the second female mold cavity;

[0071] 2) Select low-density high-silica fiber felt for high-temperature calcination; wherein, the high-temperature calcination process is to raise the temperature to 700°C and keep it warm for 30 minutes. The density of the low-density high-silica fiber felt after calcination is 0.19g / cm 3 ;

[0072] 3) The low-density high-silica fiber felt calcined at high temperature is wrapped around the outer surface of the metal rudder core 1 in accordance with the shape, and the metal rudder core 1 with the low-density high-silica fiber felt calcined at high temperature is fixed inside the inner cavity of the first female mold, and low-density phenolic resin is poured into the inner cavity of the first female mold, and the mold is removed to obtain the metal rudder core 1 with a low-density thermal insulation layer 3; wherein the low-density phenolic resin is a phenolic resin model LP40 from the LP series phenolic resin produced by the North Glass Institute, with a solid content of 38% and a density of 0.98g / cm 3 , viscosity is less than 45mPa·s; the density of the phenolic resin matrix formed after curing is 0.39g / cm 3 ;

[0073] The low-density phenolic resin infusion process is as follows: the infusion pressure in the resin tank is 0.3 MPa, and the debonding and exhaust are repeated three times until there are no bubbles in the debonding hose; the first curing molding process is to heat the temperature to 80°C at a heating rate of 10°C / min and keep it at this temperature for 24 hours; after the curing is completed, it is dried at 40°C for 1 hour, and then heated to 80°C and dried for 24 hours;

[0074] 4) Select carbon fiber and use 2.5D weaving method to perform high-density contour weaving to obtain a high-density carbon fiber preform, and perform antioxidant treatment on the high-density carbon fiber preform; wherein the density of the high-density carbon fiber preform is 0.78g / cm 3 ; The antioxidant treatment process comprises the following steps: dipping the high-density carbon fiber preform in a 12wt% polycarbosilane / xylene solution for 3h, drying and coating the surface with a polycarbosilane antioxidant layer;

[0075] 5) The high-density carbon fiber preform after antioxidant treatment is coated on the outer surface of the metal rudder core 1 with the low-density thermal insulation layer 3, and the metal rudder core 1 with the low-density thermal insulation layer 3 coated with the high-density carbon fiber preform after antioxidant treatment is fixed in the inner cavity of the second female mold, and high-density phenolic resin is poured into the inner cavity of the second female mold, and a second curing molding is performed, demolding, and machining is performed to obtain a high-density anti-ablation layer 4, thereby preparing a gradient density phenolic resin-based air rudder; wherein the high-density phenolic resin is a phenolic resin model Z615101 in the RTM series of phenolic resins produced by North Glass Institute, with a solid content of 87% and a density of 1.12 g / cm 3 , with a viscosity of 970 mPa·s; the density of the phenolic resin matrix formed after curing is 1.21 g / cm 3 ;

[0076] The high-density phenolic resin infusion process parameters are as follows: vacuuming the mold cavity to below -0.1MPa, auxiliary pressurizing the resin tank to 1.5MPa, and repeatedly degassing the glue and exhausting four times until there are no bubbles in the glue discharge hose; the second curing molding process is heating to 180°C at a rate of 10°C / min and keeping the temperature for 18 hours; and then cooling naturally after curing.

[0077] After testing, the comprehensive density of the gradient density phenolic resin air rudder heat protection material obtained by this method is 0.73g / cm 3 The thermal conductivity of the insulation layer is 0.07W / m·K, the thermal conductivity of the ablation layer is 0.35W / m·K, and the comprehensive thermal conductivity is 0.17W / m·K.

[0078] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a gradient density phenolic resin-based air rudder, characterized by: The steps include: 1) preparing a first female mold assembly having a first female mold cavity and a second female mold assembly having a second female mold cavity; wherein the cross-sectional area of ​​the first female mold cavity is smaller than the cross-sectional area of ​​the second female mold cavity; 2) selecting a low-density high-silica fiber felt, calcining it at a high temperature, and wrapping the calcined low-density high-silica fiber felt on the outer surface of the metal rudder core (1) to obtain a first prefabricated part; 3) fixing the first prefabricated part in the inner cavity of the first female mold, pouring low-density phenolic resin into the inner cavity of the first female mold, performing a first curing and forming process, and demoulding to obtain a metal rudder core (1) coated with a low-density heat insulation layer (3); 4) wrapping the high-density carbon fiber preform after the anti-oxidation treatment around the low-density thermal insulation layer (3) to obtain a second preform; 5) fixing the second preform in the inner cavity of the second female mold, pouring high-density phenolic resin into the inner cavity of the second female mold, curing and molding for a second time, demoulding, machining, forming a high-density anti-ablation layer (4) outside the low-density thermal insulation layer (3), and obtaining a gradient density phenolic resin-based air rudder; in step 2), the high-temperature calcination process is to raise the temperature to 600-800°C and keep the temperature for 30-90 minutes, and the density of the low-density high-silica fiber felt after calcination is 0.18-0.23 g / cm 3 In step 3), the solid content of the low-density phenolic resin is 30 to 50%, and the density is 0.95 to 1.05 g / cm 3 , viscosity is less than 50mPa·s; In step 4), the density of the high-density carbon fiber preform is 0.75 to 0.95 g / cm 3 The antioxidant treatment process comprises the following steps: immersing a high-density carbon fiber preform in a 10-15wt% polycarbosilane / xylene solution for 3-5 hours, drying the preform, and coating the preform with a polycarbosilane antioxidant layer; wherein the residual weight of the polycarbosilane after pyrolysis at 800°C is greater than 70%; In step 5), the solid content of the high-density phenolic resin is 85-90%, and the density is 1.05-1.15 g / cm 3 , viscosity is 800~1000mPa·s.

2. The method for preparing a gradient density phenolic resin-based air rudder according to claim 1, characterized in that: In step 3), the low-density phenolic resin is injected into the first female mold cavity at an injection pressure of 0.3 to 0.5 MPa; the first curing molding process is to heat the material to 80 to 100° C. at a heating rate of 10° C. / min and keep the temperature for 12 to 36 hours; after curing, the material is dried at 40 to 60° C. for 12 to 24 hours, and then heated to 80 to 100° C. and dried for 12 to 24 hours.

3. The method for preparing a gradient density phenolic resin-based air rudder according to claim 2, characterized in that: In step 5), before pouring high-density phenolic resin into the inner cavity of the second female mold, the inner cavity of the second female mold is first evacuated to below -0.1 MPa. During pouring, the high-density phenolic resin tank is auxiliary pressurized to 1 to 3 MPa; the second curing molding process is to heat the temperature to 180 to 200° C. at a heating rate of 10° C. / min and keep the temperature for 12 to 24 hours; and naturally cool after curing is completed.

4. A gradient density phenolic resin-based air rudder obtained by the method for preparing a gradient density phenolic resin-based air rudder according to any one of claims 1 to 3, characterized in that: The invention comprises a metal rudder core (1), wherein the metal rudder core (1) is sequentially coated with a low-density heat-insulating layer (3) and a high-density anti-ablation layer (4); The low-density heat-insulating layer (3) is obtained by curing a low-density high-silica fiber felt calcined at high temperature with a low-density phenolic resin through an RTM process, and the high-density anti-ablation layer (4) is obtained by curing a high-density carbon fiber preform after an anti-oxidation treatment with a high-density phenolic resin through an RTM process.

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