Rudder heat-proof cup suitable for aerobic long time and preparation method of rudder heat-proof cup

Abstract

The invention relates to the technical field of high-temperature fire-resistant composite materials, and provides a rudder heat-proof cup suitable for aerobic long time and a preparation method of the rudder heat-proof cup. The rudder heat-proof cup sequentially comprises an anti-oxidation and ablation-resistant layer prepared from polycarbosilane modified 2.5 D quartz fabric / medium-density phenolic aldehyde, a barrier layer prepared from a metal material and a heat insulation layer prepared from quartz fiber cloth reinforced low-density phenolic aldehyde from the outer layer to the inner layer, the manufacturing method mainly comprises the following steps: putting the heat insulation layer fiber cloth, the metal barrier layer and the anti-oxidation ablation-resistant layer into a forming mold by using 2.5 D quartz fabric; a double-cavity structure is achieved through mold design, and medium-density phenolic aldehyde and low-density phenolic aldehyde are adopted for impregnation and curing at the same time; brushing a polycarbosilane modified anti-oxidation ablation-resistant layer; and finally processing to obtain the rudder heat-proof cup. Compared with a traditional material, the ablation retreating amount of the anti-oxidation ablation layer material of the rudder heat-proof cup is reduced by 90% or above, the internal temperature is greatly reduced through metal phase change and low-density heat insulation, and the anti-oxidation ablation layer material is suitable for thermal protection of an aerobic long-time rudder shaft.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature refractory composite material technology, and particularly relates to a rudder heat shield cup suitable for long-term oxygen exposure and its preparation method. Background Technology

[0002] Air rudders are crucial components for controlling an aircraft's flight attitude. During flight attitude control, the air rudders need to rotate continuously to maintain the aircraft's posture. The rigidity and strength of the rudder shaft are important technical indicators for aircraft stability control. Generally, heat shields are used to protect the rudder shaft from heat, ensuring its normal operation. Ballistic reentry missiles face a high-enthalpy, high-heat-flux aerodynamic environment near the air rudder shaft, with surface temperatures exceeding 2300℃. Reentry time is approximately tens of seconds. Heat shields commonly use high-density quartz / phenolic resin for thermal protection, reducing the rudder shaft temperature and ensuring high rigidity. In order to better penetrate enemy missile interception systems, missile technology has evolved from ballistic reentry to long-duration maneuvering gliding with oxygen in the atmosphere. The flight time of missiles in the atmosphere has increased dramatically from tens of seconds to hundreds or even thousands of seconds, which puts forward the requirements for long-term oxidation resistance and long-term heat insulation for rudder heat shields. Traditional high-density quartz / phenolic resin has high thermal conductivity and poor heat insulation ability, and pyrolytic carbon has poor oxidation resistance. It also has a large amount of erosion after long-term oxidation, which can no longer meet the design and use requirements of new missile rudder heat shields. Summary of the Invention

[0003] The purpose of this application is to provide a rudder heat shield suitable for long-term oxygen exposure and its preparation method. Traditional single-structure high-density quartz / phenolic rudder heat shields have high thermal conductivity, poor heat insulation, poor pyrolytic carbon oxidation resistance, and large amount of erosion after long-term oxidation, which cannot meet the design and use requirements of new missile rudder heat shields.

[0004] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0005] This application provides a rudder heat shield cup for long-term aerobic operation. The rudder heat shield cup comprises, from the outer layer to the inner layer, an anti-oxidation and ablation resistant layer, a barrier layer, and a heat insulation layer. The anti-oxidation and ablation resistant layer is made of a composite material of medium-density phenolic resin reinforced with 2.5D quartz fiber fabric, and the composite material is further modified with polycarbosilane. The barrier layer is made of metal with a thickness of 0.1-0.3 mm. The heat insulation layer is made of low-density phenolic resin reinforced with quartz fiber cloth.

[0006] As one possible design, the polycarbosilane contains both silane-hydrogen bonds and vinyl groups. When using a platinum catalyst, the maximum curing temperature of the polycarbosilane is ≤120°C, and the ceramic yield (1000°C, N2 atmosphere) is ≥70%.

[0007] As one possible design, the metal of the barrier layer is one of copper, aluminum, iron, zinc, or magnesium.

[0008] As one possible design, medium-density phenolic resin and low-density phenolic resin can be any one of barium phenolic resin, aminophenolic resin, high-carbon phenolic resin, or magnesium phenolic resin. The adhesive content of medium-density phenolic resin is 45-70%, and the adhesive content of low-density phenolic resin is 15-35%.

[0009] On the other hand, this application provides a method for preparing a rudder heat shield cup suitable for long-duration aerobic exercise, comprising the following steps:

[0010] S1: Prepare the molding die, which includes a female mold, a male mold, a front end cap, and a rear end cap;

[0011] S2 uses quartz fiber cloth to wrap the heat insulation layer onto the surface of the male mold;

[0012] S3: The barrier layer is made of metal and placed over the quartz fiber cloth;

[0013] S4: The anti-oxidation and ablation-resistant layer is formed by wrapping a 2.5D quartz fiber fabric over the outside of the barrier layer;

[0014] S5: Assemble the female mold, male mold, front end cap, and rear end cap together;

[0015] S6: Impregnated and cured with both medium-density and low-density phenolic resins;

[0016] S7: Disassemble the mold; keep the product at 120-180℃ for 5-10 hours;

[0017] S8: Modified with polycarbosilane for oxidation and ablation resistance;

[0018] S9: Machining to obtain the rudder heat shield cup.

[0019] As one possible design, the molding die described in S1 has a cylindrical female mold with the same inner diameter as the outer diameter of the rudder heat shield cup; a cylindrical male mold with the same diameter as the inner diameter of the rudder heat shield cup; a male mold positioning groove with a depth of 1-5mm and a diameter 0.1-0.4mm larger than the male mold diameter is provided in the middle of both the front and rear end caps; both the front and rear end caps have an inner circular sealing gasket and an outer circular sealing gasket, the inner circular sealing gasket having the same centerline diameter as the rudder heat shield cup blocking layer, and the outer circular sealing gasket having a centerline diameter 4-10mm larger than the inner diameter of the female mold; the front end cap has several glue inlets, the positions of which correspond to the anti-oxidation and ablation-resistant layer and the heat insulation layer, and the rear end cap has several glue outlets, the positions of which correspond to the anti-oxidation and ablation-resistant layer and the heat insulation layer;

[0020] As one possible design, S5 describes assembling the female mold, male mold, front end cap, and rear end cap together, including the following method:

[0021] The male mold, along with its outer material, is inserted into the female mold;

[0022] The male mold is inserted into the male mold positioning grooves of the front and rear end caps;

[0023] The inner circular sealing gaskets of the front and rear end caps are bonded to the metal of the barrier layer, while the outer circular sealing gaskets are bonded to the end face of the female mold, forming a dual-cavity structure that can be impregnated with two different phenolic resins at the same time.

[0024] As a possible design, from S2 to S9, the positive mold is used for positioning and shaping throughout the process to avoid deformation of the inner diameter of the rudder heat shield cup during the manufacturing process.

[0025] As one possible design, simultaneous impregnation and curing with medium-density and low-density phenolic resins includes the following methods:

[0026] Vacuum the outlet of the molding mold. When the vacuum degree is ≤-0.09Mpa, medium-density phenolic resin is pumped into the cavity of the corresponding anti-oxidation and ablation-resistant layer of the molding mold through the inlet, and low-density phenolic resin is pumped into the cavity of the corresponding heat insulation layer of the molding mold until the outlets of both cavities are dispensing resin.

[0027] Stop the vacuum, seal the outlet, and apply pressure to the inlet at 0.2-2 MPa for 3-8 hours.

[0028] Depressurize and close the inlet; heat the mold at 90℃ for 2-4 hours; 120℃ for 2-4 hours; 140℃ for 2-4 hours; and 160℃ for 4-8 hours.

[0029] As one possible design, the modification of polycarbosilane into an oxidation-resistant and ablation-resistant layer includes the following methods:

[0030] Apply adhesive: Apply polycarbosilane to the surface of the anti-oxidation and ablation-resistant layer until it no longer penetrates;

[0031] Curing: 60℃, 4-8h; 100℃, 4-8h;

[0032] Repeat the above adhesive application and curing process 1-4 times until the ratio of polycarbosilane adhesive used in the first application to that used in the second application is ≤10%.

[0033] The beneficial effects of this invention are as follows:

[0034] 1. The selected polycarbosilane is cured at low temperatures, and the curing process has no impact on the performance of medium-density phenolic resin. Polycarbosilane contains a large amount of silicon in its molecular structure, exhibiting excellent heat resistance, oxidation resistance, and ablation resistance. The introduction of polycarbosilane into the high-porosity medium-density phenolic resin in the rudder heat shield cup can significantly improve the problem of high-temperature oxidation resistance of phenolic pyrolysis carbon, reducing the ablation retreat of the material under oxygen conditions. The 1000s electric arc wind tunnel ablation test results show that, compared with the quartz / phenolic resin of traditional rudder heat shield cups, the ablation retreat of the antioxidant ablation layer material of this patented rudder heat shield cup is reduced by more than 90%, meeting the shape ablation requirements of the rudder heat shield cup under long-term oxygen conditions.

[0035] 2. Regarding reducing the inner surface temperature of the rudder heat shield, on the one hand, a metal barrier layer is introduced into the rudder heat shield. The metal barrier layer absorbs a large amount of heat through melting and vaporization phase changes. At the same time, the gap between the anti-oxidation and ablation layer formed by the metal loss of the barrier layer and the heat insulation layer is used to achieve thermal circuit breaking. On the other hand, the heat insulation layer is made of low-density phenolic resin, which has low density and low thermal conductivity. Through the above two measures, the inner surface temperature of the rudder heat shield can be significantly reduced, meeting the design requirements for the inner surface temperature of the rudder heat shield for long-term oxygenation.

[0036] 3. By introducing a metal barrier layer and molding die structure design into the rudder heat shield cup, a dual-cavity structure is formed, enabling simultaneous impregnation and curing of two different phenolic resins. This effectively solves the conflict problem between the high density of the outer layer and the low density of the inner layer of the rudder heat shield cup. The entire process utilizes positive mold positioning and shaping, resulting in rudder heat shield cups with high dimensional accuracy, small processing volume, and high production efficiency. The medium-density phenolic resin is modified by brushing with low-temperature curing polycarbon silane, and the metal barrier layer prevents the resin from entering the low-density insulation layer. The modification process is simple and efficient. Through the above design and process innovations, rapid and low-cost preparation of rudder heat shield cups suitable for long-term aerobic conditions is achieved. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of a heat-resistant cup suitable for long-duration aerobic operation, where the left image is a schematic diagram of the overall appearance and the right image is a schematic diagram of the cross-section.

[0039] Figure 2 This is a breakdown diagram of the molding die;

[0040] Figure 3 The diagram shows the structure of the front and rear end caps, with the left image showing the front end cap and the right image showing the rear end cap.

[0041] Figure 4 This is a schematic diagram showing the positional relationships during the mold assembly process;

[0042] Figure 5 This is a schematic diagram showing the internal structural relationships of the mold after assembly.

[0043] Figure 6 A schematic diagram of the ablation sample of the rudder heat shield cup;

[0044] Figure 7 A schematic diagram showing the positional relationship of the rudder heat shield cup in the electric arc wind tunnel test.

[0045] In the diagram: 1- Suitable for long-term oxygen-containing rudder heat shield; 11- Antioxidant and ablation-resistant layer; 12- Barrier layer; 13- Insulation layer; 2- Molding mold; 21- Female mold; 22- Male mold; 23- Front end cap; 24- Rear end cap; 25- Groove; 26- Inner circular sealing gasket; 27- Outer circular sealing gasket; 28- Inlet; 29- Outlet; 3- Closed inner cavity; 4- Closed outer cavity; 5- Ablation sample; 51- Rudder heat shield blank; 52- Metal rudder shaft; 53- Temperature sensor; 6- Arc wind tunnel Detailed Implementation

[0046] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0047] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0048] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0049] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0050] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a well-known unit of mass in the chemical industry, such as µg, mg, g, or kg.

[0051] The following description is based on specific embodiments.

[0052] Example 1

[0053] Suitable for long-term aerobic exercise, such as the rudder heat-resistant cup structure Figure 1 As shown, the rudder heat shield 1 comprises, from the outermost layer to the innermost layer, an antioxidant and ablation-resistant layer 11, a barrier layer 12, and a heat insulation layer 13, with thicknesses of 5mm, 0.2mm, and 15mm respectively. The inner diameter of the rudder heat shield is 50mm, and the outer diameter is 90.4mm. The antioxidant and ablation-resistant layer 11 is made of a composite material of medium-density phenolic resin reinforced with 2.5D quartz fiber fabric. The medium-density phenolic resin is barium phenolic resin, and the resin content is 50%. The composite material is further modified with polycarbosilane, which contains both silicon-hydrogen bonds and vinyl groups. When using a platinum catalyst, the maximum curing temperature of polycarbosilane is 100℃, and the ceramic yield (1000℃, N2 atmosphere) is 73%. The barrier layer 12 is made of metallic aluminum. The heat insulation layer 13 is made of low-density phenolic resin reinforced with quartz fiber cloth. The low-density phenolic resin is barium phenolic resin, and the resin content is 25%.

[0054] The specific preparation steps for a heat-resistant rudder cup suitable for long-duration aerobic exercise are as follows:

[0055] S1: Prepare molding die 2, the structure of molding die 2 is as follows Figure 2 As shown, it includes a female mold 21, a male mold 22, a front plug 23, and a rear plug 24; the female mold 21 is cylindrical, with an inner diameter that is the same as the outer diameter of the rudder heat shield, and a diameter of 90.4 mm; the male mold 22 is cylindrical, with a diameter that is the same as the inner diameter of the rudder heat shield, and a diameter of 50 mm; the structures of the front plug 23 and the rear plug 24 are as follows. Figure 3 As shown, each has a male mold positioning groove 25 in the middle, with a depth of 2mm and a diameter 0.2mm larger than the diameter of the male mold; both the front cover 23 and the rear cover 24 have an inner circular sealing gasket 26 and an outer circular sealing gasket 27. The inner circular sealing gasket 26 has the same centerline diameter as the rudder heat shield cup blocking layer 12, with a diameter of 80.2mm, a width of 3mm, and a height of 1mm. The centerline diameter of the outer circular sealing gasket 27 is 5mm larger than the inner diameter of the female mold 21; the front cover 23 has 8 glue inlets 28, the positions of which correspond to the anti-oxidation and ablation-resistant layer and the heat insulation layer; the rear cover 24 has 8 glue outlets 29, the positions of which correspond to the anti-oxidation and ablation-resistant layer and the heat insulation layer.

[0056] S2 uses quartz fiber cloth to wrap the heat insulation layer onto the surface of the male mold. The thickness of a single layer of quartz cloth is about 0.2 mm, and about 75 layers are wrapped.

[0057] S3: The barrier layer is made of aluminum and placed over the quartz fiber cloth;

[0058] S4: The anti-oxidation and ablation resistant layer is formed by wrapping a 2.5D quartz fiber fabric around the barrier layer. The quartz fabric has a fiber content of about 50%, and the fabric is cylindrical with an inner diameter of about 80.4 mm and an outer diameter of about 90.4 mm.

[0059] S5: Press Figure 4 Assemble the female mold 21, male mold 22, front cover 23, and rear cover 24 together. The specific steps are as follows: First, insert the male mold 22, along with its outer material, into the female mold 21. Then, insert the male mold 22 into the male mold positioning grooves 25 of the front cover 23 and the rear cover 24. Finally, connect the front cover 23 and the rear cover 24 to the female mold 21. The connection can be achieved using screws, clamps, clips, or other methods. After assembly, the internal positional relationships of the molding die are as follows: Figure 5 As shown, the inner circular sealing gasket 26 is bonded to the metal of the barrier layer, and the outer circular sealing gasket 27 is bonded to the end face of the female mold 21, forming a double-cavity structure with a closed inner cavity 3 and a closed outer cavity 4.

[0060] S6: Medium-density phenolic resin and low-density phenolic resin are simultaneously impregnated and cured. The specific operation method is as follows: Vacuum the outlet of the molding mold. When the vacuum degree is ≤-0.09 MPa, through the inlet, pump the medium-density phenolic resin into the cavity corresponding to the anti-oxidation and ablation-resistant layer of the molding mold, and pump the low-density phenolic resin into the cavity corresponding to the heat insulation layer of the molding mold, until the outlets of both cavities discharge resin; stop the vacuum, seal the outlet, pressurize the inlet to 0.5 MPa, and maintain the pressure for 6 hours; release the pressure, close the inlet, and heat the mold: 90℃ for 2 hours; 120℃ for 2 hours; 140℃ for 2 hours; 160℃ for 4 hours.

[0061] S7: Disassemble the mold; keep the product at 130℃ for 8 hours;

[0062] S8: Polycarbosilane is used to modify the anti-oxidation and ablation resistant layer. The specific operation method is as follows: apply polycarbosilane to the surface of the anti-oxidation and ablation resistant layer until it no longer penetrates; heat to cure, 60℃, 5h; 100℃, 5h; repeat the above brushing-curing operation twice, and the ratio of the amount of polycarbosilane used in the last brushing to that used in the first brushing is 3%.

[0063] S9: Machining to obtain the rudder heat shield cup.

[0064] Example 2

[0065] Suitable for long-term aerobic exercise, such as the rudder heat-resistant cup structure Figure 1 As shown, the rudder heat shield 1 comprises, from the outermost layer to the innermost layer, an antioxidant and ablation-resistant layer 11, a barrier layer 12, and a heat insulation layer 13, with thicknesses of 5mm, 0.2mm, and 15mm respectively. The inner diameter of the rudder heat shield is 50mm, and the outer diameter is 90.4mm. The antioxidant and ablation-resistant layer 11 is made of a composite material of medium-density phenolic resin reinforced with 2.5D quartz fiber fabric. The medium-density phenolic resin is selected as acetal phenolic resin, and the resin content of the medium-density phenolic resin is 60%. The composite material is further modified by polycarbosilane, which contains both silicon-hydrogen bonds and vinyl groups. When using a platinum catalyst, the maximum curing temperature of polycarbosilane is 100℃, and the ceramic yield (1000℃, N2 atmosphere) is 78%. The barrier layer 12 is made of metallic aluminum. The heat insulation layer 13 is made of low-density phenolic resin reinforced with quartz fiber cloth. The low-density phenolic resin is selected as acetal phenolic resin, and the resin content of the low-density phenolic resin is 30%.

[0066] The specific preparation steps for a heat-resistant rudder cup suitable for long-duration aerobic exercise are as follows:

[0067] S1: Prepare molding die 2, the structure of molding die 2 is as follows Figure 2 As shown, it includes a female mold 21, a male mold 22, a front plug 23, and a rear plug 24; the female mold 21 is cylindrical, with an inner diameter that is the same as the outer diameter of the rudder heat shield, and a diameter of 90.4 mm; the male mold 22 is cylindrical, with a diameter that is the same as the inner diameter of the rudder heat shield, and a diameter of 50 mm; the structures of the front plug 23 and the rear plug 24 are as follows. Figure 3 As shown, each has a male mold positioning groove 25 in the middle, with a depth of 3mm and a diameter 0.3mm larger than the diameter of the male mold; both the front cover 23 and the rear cover 24 have an inner circular sealing gasket 26 and an outer circular sealing gasket 27. The inner circular sealing gasket 26 has the same centerline diameter as the rudder heat shield cup blocking layer 12, with a diameter of 80.2mm, a width of 3mm, and a height of 1mm. The centerline diameter of the outer circular sealing gasket 27 is 6mm larger than the inner diameter of the female mold 21; the front cover 23 has 8 glue inlets 28, the positions of which correspond to the anti-oxidation and ablation-resistant layer and the heat insulation layer; the rear cover 24 has 8 glue outlets 29, the positions of which correspond to the anti-oxidation and ablation-resistant layer and the heat insulation layer.

[0068] S2 uses quartz fiber cloth to wrap the heat insulation layer onto the surface of the male mold. The thickness of a single layer of quartz cloth is about 0.2 mm, and about 75 layers are wrapped.

[0069] S3: The barrier layer is made of aluminum and placed over the quartz fiber cloth;

[0070] S4: The anti-oxidation and ablation resistant layer is formed by wrapping a 2.5D quartz fiber fabric around the barrier layer. The quartz fabric has a fiber content of about 53%, and the fabric is cylindrical with an inner diameter of about 80.4 mm and an outer diameter of about 90.4 mm.

[0071] S5: Press Figure 4Assemble the female mold 21, male mold 22, front cover 23, and rear cover 24 together. The specific steps are as follows: First, insert the male mold 22, along with its outer material, into the female mold 21. Then, insert the male mold 22 into the male mold positioning grooves 25 of the front cover 23 and the rear cover 24. Finally, connect the front cover 23 and the rear cover 24 to the female mold 21. The connection can be achieved using screws, clamps, clips, or other methods. After assembly, the internal positional relationships of the molding die are as follows: Figure 5 As shown, the inner circular sealing gasket 26 is bonded to the metal of the barrier layer, and the outer circular sealing gasket 27 is bonded to the end face of the female mold 21, forming a double-cavity structure with a closed inner cavity 3 and a closed outer cavity 4.

[0072] S6: Medium-density phenolic resin and low-density phenolic resin are simultaneously impregnated and cured. The specific operation method is as follows: Vacuum the outlet of the molding mold. When the vacuum degree is ≤-0.09 MPa, through the inlet, pump the medium-density phenolic resin into the cavity corresponding to the anti-oxidation and ablation-resistant layer of the molding mold, and pump the low-density phenolic resin into the cavity corresponding to the heat insulation layer of the molding mold, until the outlets of both cavities discharge resin; stop the vacuum, seal the outlet, pressurize the inlet to 1 MPa, and maintain the pressure for 4 hours; release the pressure, close the inlet, and heat the mold: 90℃ for 3 hours; 120℃ for 3 hours; 140℃ for 3 hours; 160℃ for 5 hours.

[0073] S7: Disassemble the mold; keep the product at 150℃ for 7 hours;

[0074] S8: Polycarbosilane is used to modify the anti-oxidation and ablation resistant layer. The specific operation method is as follows: apply polycarbosilane to the surface of the anti-oxidation and ablation resistant layer until it no longer penetrates; heat to cure, 60℃, 6h; 100℃, 6h; repeat the above brushing-curing operation once, and the ratio of the amount of polycarbosilane used in the brushing to that used in the first time is 7%.

[0075] S9: Machining to obtain the rudder heat shield cup.

[0076] Example 3

[0077] Suitable for long-term aerobic exercise, such as the rudder heat-resistant cup structure Figure 1As shown, the rudder heat shield 1 comprises, from the outermost layer to the innermost layer, an antioxidant and ablation-resistant layer 11, a barrier layer 12, and a heat insulation layer 13, with thicknesses of 5mm, 0.2mm, and 15mm respectively. The inner diameter of the rudder heat shield is 50mm, and the outer diameter is 90.4mm. The antioxidant and ablation-resistant layer 11 is made of a composite material of medium-density phenolic resin reinforced with 2.5D quartz fiber fabric. The medium-density phenolic resin is selected from magnesium phenolic resin, and the resin content of the medium-density phenolic resin is 67%. The composite material is further modified from polycarbosilane. Polycarbosilane contains both silicon-hydrogen bonds and vinyl groups. When using a platinum catalyst, the maximum curing temperature of polycarbosilane is 100℃, and the ceramic yield (1000℃, N2 atmosphere) is 77%. The barrier layer 12 is made of metallic copper. The heat insulation layer 13 is made of low-density phenolic resin reinforced with quartz fiber cloth. The low-density phenolic resin is selected from magnesium phenolic resin, and the resin content of the low-density phenolic resin is 35%.

[0078] The specific preparation steps for a heat-resistant rudder cup suitable for long-duration aerobic exercise are as follows:

[0079] S1: Prepare molding die 2, the structure of molding die 2 is as follows Figure 2 As shown, it includes a female mold 21, a male mold 22, a front plug 23, and a rear plug 24; the female mold 21 is cylindrical, with an inner diameter that is the same as the outer diameter of the rudder heat shield, and a diameter of 90.4 mm; the male mold 22 is cylindrical, with a diameter that is the same as the inner diameter of the rudder heat shield, and a diameter of 50 mm; the structures of the front plug 23 and the rear plug 24 are as follows. Figure 3 As shown, each has a male mold positioning groove 25 in the middle, with a depth of 5mm and a diameter 0.4mm larger than the male mold diameter; both the front cover 23 and the rear cover 24 have an inner circular sealing gasket 26 and an outer circular sealing gasket 27. The inner circular sealing gasket 26 has the same centerline diameter as the rudder heat shield cup blocking layer 12, with a diameter of 80.2mm, a width of 3mm, and a height of 1mm. The centerline diameter of the outer circular sealing gasket 27 is 8mm larger than the inner diameter of the female mold 21; the front cover 23 has 8 glue inlets 28, the positions of which correspond to the anti-oxidation and ablation-resistant layer and the heat insulation layer; the rear cover 24 has 8 glue outlets 29, the positions of which correspond to the anti-oxidation and ablation-resistant layer and the heat insulation layer.

[0080] S2 uses quartz fiber cloth to wrap the heat insulation layer onto the surface of the male mold. The thickness of a single layer of quartz cloth is about 0.2 mm, and about 75 layers are wrapped.

[0081] S3: The barrier layer is made of copper and placed over the quartz fiber cloth;

[0082] S4: The anti-oxidation and ablation-resistant layer is formed by wrapping a 2.5D quartz fiber fabric around the barrier layer. The quartz fabric has a fiber content of about 55%, and the fabric is cylindrical with an inner diameter of about 80.4 mm and an outer diameter of about 90.4 mm.

[0083] S5: Press Figure 4Assemble the female mold 21, male mold 22, front cover 23, and rear cover 24 together. The specific steps are as follows: First, insert the male mold 22, along with its outer material, into the female mold 21. Then, insert the male mold 22 into the male mold positioning grooves 25 of the front cover 23 and the rear cover 24. Finally, connect the front cover 23 and the rear cover 24 to the female mold 21. The connection can be achieved using screws, clamps, clips, or other methods. After assembly, the internal positional relationships of the molding die are as follows: Figure 5 As shown, the inner circular sealing gasket 26 is bonded to the metal of the barrier layer, and the outer circular sealing gasket 27 is bonded to the end face of the female mold 21, forming a double-cavity structure with a closed inner cavity 3 and a closed outer cavity 4.

[0084] S6: Medium-density phenolic resin and low-density phenolic resin are simultaneously impregnated and cured. The specific operation method is as follows: Vacuum the outlet of the molding mold. When the vacuum degree is ≤-0.09 MPa, through the inlet, pump the medium-density phenolic resin into the cavity corresponding to the anti-oxidation and ablation-resistant layer of the molding mold, and pump the low-density phenolic resin into the cavity corresponding to the heat insulation layer of the molding mold, until the outlets of both cavities discharge resin; stop the vacuum, seal the outlet, and pressurize the inlet to 1.6 MPa, holding the pressure for 3 hours; release the pressure, close the inlet, and heat the mold: 90℃ for 4 hours; 120℃ for 4 hours; 140℃ for 4 hours; 160℃ for 7 hours.

[0085] S7: Disassemble the mold; keep the product at 180℃ for 5 hours;

[0086] S8: Polycarbosilane is used to modify the anti-oxidation and ablation resistant layer. The specific operation method is as follows: apply polycarbosilane to the surface of the anti-oxidation and ablation resistant layer until it no longer penetrates; heat to cure, 60℃, 4-8h; 100℃, 4-8h; repeat the above brushing-curing operation 3 times until the ratio of the amount of polycarbosilane used in the brushing to that used in the first time is 1%.

[0087] S9: Machining to obtain the rudder heat shield cup.

[0088] Comparative Example 1

[0089] The step of S3, in which the aluminum-made cylinder of the barrier layer is placed over the quartz fiber cloth, is omitted. The other steps are exactly the same as in Example 1. The prepared rudder heat shield cup does not contain a metal barrier layer.

[0090] Comparative Example 2

[0091] The content of medium-density phenolic resin was increased to 80%, while other raw materials and steps were exactly the same as in Example 1.

[0092] Comparative Example 3

[0093] In the S8 operation, medium-density phenolic resin is used instead of polycarbosilane. Other raw materials and steps are exactly the same as in Example 1. The antioxidant and ablation-resistant layer of the prepared rudder heat shield does not contain polycarbosilane, but is the traditional quartz / phenolic resin.

[0094] Comparative Example 4

[0095] The inner circular sealing gaskets of the front and rear end caps of the molding die were removed, and the other steps were exactly the same as in Example 1.

[0096] Take the rudder heat shield blanks obtained in step S8 of Examples 1-3 and Comparative Examples 1-4, and follow the... Figure 6 A test specimen for arc wind tunnel ablation was prepared. A rudder heat shield blank 5-1 was fitted over a metal rudder shaft 5-2, and a temperature sensor 5-3 was attached to the inner surface of the rudder heat shield blank 5-1. The heat flux for the arc wind tunnel test was 2.3 ± 0.2 MW / m². 2 The test lasted 1000 seconds. The ablation retreat of the test rudder heat shield blank and its inner wall stopping temperature were measured. The positional relationship between the arc wind tunnel and the ablation test specimen was as follows: Figure 7 As shown.

[0097] The ablation test results of the rudder heat shield blanks prepared in Examples 1-3 and Comparative Examples 1-4 are shown in Table 1 below. The ablation retreat of the rudder heat shield blanks in Examples 1-3 and Comparative Examples 1-4 are 0.23 mm, 0.31 mm, 0.26 mm, 0.27 mm, 2.4 mm, 4.5 mm, and 0.19 mm, respectively. The inner wall stopping temperatures of the rudder heat shield blanks in Examples 1-3 and Comparative Examples 1-4 are 375℃, 398℃, 405℃, 1100℃, 550℃, 870℃, and 478℃, respectively.

[0098] Table 1 Summary of ablation test results for the rudder heat shield blank

[0099] Examples / Comparative Examples ablation retreat (mm) Parking temperature ℃ Remark Example 1 0.23 375 / Example 2 0.31 398 / Example 3 0.26 405 / Comparative Example 1 0.27 1100 Remove the barrier layer Comparative Example 2 2.4 550 Increase the content of medium-density phenolic resin Comparative Example 3 4.5 870 Antioxidant and ablation resistant layer does not contain polycarbosilane Comparative Example 4 0.19 478 The inner circular sealing gasket of the mold was removed.

[0100] The ablation test results of the rudder heat shield blanks prepared in Examples 1-3 and Comparative Examples 1-4 show that:

[0101] 1. The anti-oxidation and ablation-resistant layer of the rudder heat shield in Examples 1-3 is modified with polycarbosilane. The resin matrix has good anti-oxidation ability, and the ablation retreat of the sample is small. The rudder heat shield is equipped with a metal barrier layer and a low-density heat insulation layer. The metal barrier layer absorbs heat through solid-liquid phase change and liquid-gas phase change, and at the same time forms a physical heat conduction circuit. Combined with the internal low-density heat insulation layer, the stopping temperature of the inner wall of the rudder heat shield is low. The rudder heat shield in Examples 1-3 has excellent heat protection and heat insulation performance and is suitable for the thermal protection of the rudder shaft during long-term oxygen exposure.

[0102] 2. In Comparative Example 1, the metal barrier layer in the rudder heat shield cup was removed. When S8 was modified with polycarbosilane for anti-oxidation and ablation resistance, the polycarbosilane filled the heat insulation layer, which greatly increased the thermal conductivity of the heat insulation layer and lost its heat insulation function. The sample had the highest shutdown temperature.

[0103] 3. Comparative Example 2 increased the resin content of medium-density phenolic resin, reduced the polycarbosilane content of the antioxidant and ablation-resistant layer, and decreased the antioxidant performance of the resin matrix at high temperatures, resulting in a significant increase in the amount of ablation retreat compared to Example 1, and an increase in the shutdown temperature of approximately 150°C.

[0104] 4. In Comparative Example 3, medium-density phenolic resin was used instead of polycarbosilane during S8 operation. The antioxidant and ablation-resistant layer of the prepared rudder heat shield did not contain polycarbosilane and was a traditional quartz / phenolic resin. The resin matrix of this material did not contain antioxidant polycarbosilane. The phenolic pyrolysis carbon was rapidly oxidized in the presence of oxygen. The sample had the largest ablation retreat and a significantly higher shutdown temperature.

[0105] 5. In Comparative Example 4, the inner circular sealing gaskets of the front and rear end caps of the molding die were removed. After operation S5, a double-cavity structure was not formed inside the mold. During impregnation in S6, the low-density phenolic portion entered the anti-oxidation and ablation-resistant layer, resulting in a higher porosity of the cured material. After modification with polycarbosilane in S8, the proportion of polycarbosilane increased, improving the oxidation resistance of the material and slightly reducing the ablation retreat of the sample. At the same time, the medium-density phenolic portion entered the heat insulation layer, resulting in a decrease in porosity and an increase in thermal conductivity of the cured material, significantly increasing the sample's stopping temperature.

[0106] Through the above experiments and analyses, it was found that the three-layer functional structure design of the rudder heatproof cup of the present invention is the key to its good long-term heat insulation performance in aerobic environments; the metal barrier layer design, mold structure design, and design of different phenolic resin contents, among other innovative measures, are the key to preparing a rudder heatproof cup suitable for long-term aerobic environments.

[0107] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A rudder heat shield cup suitable for long periods of oxygen exposure, characterized in that, The rudder heat protection cup comprises, from the outer layer to the inner layer, an oxidation-resistant and ablation-resistant layer, a barrier layer and a heat insulation layer; the oxidation-resistant and ablation-resistant layer is made of a 2.5D quartz fiber fabric reinforced medium-density phenolic compound, the compound is further modified by polycarbosilane; the barrier layer is made of metal with a thickness of 0.1-0.3 mm; and the heat insulation layer is made of a quartz fiber cloth reinforced low-density phenolic.

2. A heat shield cup suitable for long duration aerobic use according to claim 1, wherein, The polycarbosilane contains both silicon-hydrogen bonds and vinyl groups, and the highest curing temperature of the polycarbosilane is ≤120℃ when a platinum catalyst is used, and the ceramic yield (1000℃, N2 atmosphere) is ≥70%.

3. A heat shield cup suitable for long duration aerobic use according to claim 1, wherein, The metal of the barrier layer is one of copper, aluminum, iron, zinc and magnesium.

4. The heat shield cup of claim 1, wherein, The medium-density phenolic and the low-density phenolic are any one of barium phenolic, ammonia phenolic, high-carbon phenolic and magnesium phenolic, the medium-density phenolic has a glue content of 45-70%, and the low-density phenolic has a glue content of 15-35%.

5. A process for the preparation of a rudder fairing cup suitable for long periods of exposure to oxygen, according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: S1: preparing a forming mold, the forming mold comprises a female mold, a male mold, a front blocking cover and a rear blocking cover; S2: winding the heat insulation layer forming quartz fiber cloth on the surface of the male mold; S3: sleeving the barrier layer made of metal outside the quartz fiber cloth; S4: sleeving the oxidation-resistant and ablation-resistant layer forming 2.5D quartz fiber fabric outside the barrier layer; S5: assembling the female mold, the male mold, the front blocking cover and the rear blocking cover together; S6: simultaneously impregnating and curing the medium-density phenolic and the low-density phenolic; S7: disassembling the mold; and curing the product at 120-180℃ for 5-10 h; S8: modifying the oxidation-resistant and ablation-resistant layer by polycarbosilane; S9: machining to obtain the rudder heat protection cup.

6. The process for the preparation of a heat shield cup suitable for long duration aerobic use according to any one of claims 1 to 4 according to claim 5, characterized in that, The forming mold of S1, the female mold is cylindrical, the inner diameter of the female mold is the same as the outer diameter of the rudder heat protection cup; the male mold is cylindrical, the diameter of the male mold is the same as the inner diameter of the rudder heat protection cup; the middle of the front blocking cover and the rear blocking cover is provided with a male mold positioning groove, the groove depth is 1-5 mm, and the diameter is greater than the diameter of the male mold by 0.1-0.4 mm; the front blocking cover and the rear blocking cover are provided with an inner circular sealing gasket and an outer circular sealing gasket, the inner diameter of the inner circular sealing gasket is the same as the middle line diameter of the barrier layer of the rudder heat protection cup, and the middle line diameter of the outer circular sealing gasket is greater than the inner diameter of the female mold by 4-10 mm; the front blocking cover is provided with a plurality of glue inlets, which correspond to the oxidation-resistant and ablation-resistant layer and the heat insulation layer, and the rear blocking cover is provided with a plurality of glue outlets, which correspond to the oxidation-resistant and ablation-resistant layer and the heat insulation layer.

7. The process for the preparation of a heat shield cup suitable for long duration aerobic use according to any one of claims 1 to 4, according to claim 5, characterized by, The assembling of the female mold, the male mold, the front blocking cover and the rear blocking cover of S5 comprises the following method: The male mold is put into the female mold together with the material outside the male mold; The male mold is inserted into the male mold positioning groove of the front blocking cover and the rear blocking cover; The inner circular sealing gasket of the front blocking cover and the rear blocking cover is attached to the metal of the barrier layer, and the outer circular sealing gasket is attached to the end face of the female mold, forming a double-cavity structure that can simultaneously impregnate two different phenolics.

8. A process for the preparation of a heat shield cup suitable for long duration aerobic use according to any one of claims 1 to 4, according to claim 5, characterized in that, From S2 to S9, the male mold is used for positioning and shape maintaining throughout the process, so that the inner diameter of the rudder heat protection cup is prevented from being deformed during the preparation process.

9. The process for the preparation of a heat shield cup suitable for long duration aerobic use according to any one of claims 1 to 4, according to claim 5, characterized in that, The simultaneous impregnation and curing of the medium-density phenolic and the low-density phenolic comprises the following method: When the vacuum degree of the glue outlet of the forming mold is less than or equal to-0.09 MPa, the medium-density phenolic resin is pumped into the cavity corresponding to the oxidation-resistant and ablation-resistant layer of the forming mold through the glue inlet, and the low-density phenolic resin is pumped into the cavity corresponding to the heat-insulating layer of the forming mold, until the glue outlets of the two cavities are both glued; Stop vacuuming, close the glue outlet, and pressurize the glue inlet at 0.2-2 MPa for 3-8 h; Release the pressure, close the glue inlet, heat the mold at 90℃ for 2-4 h, at 120℃ for 2-4 h, at 140℃ for 2-4 h, and at 160℃ for 4-8 h.

10. The process for the preparation of a heat shield cup suitable for long duration aerobic use according to any one of claims 1 to 4, according to claim 5, characterized in that, Polycarbosilane modification of the oxidation-resistant and ablation-resistant layer, comprising the following steps: Glue brushing: brush polycarbosilane on the surface of the oxidation-resistant and ablation-resistant layer until no more penetration; Curing: 60℃ for 4-8 h, and 100℃ for 4-8 h; Repeat the above glue brushing-curing operation 1-4 times until the ratio of the amount of polycarbosilane glue used to the first time is less than or equal to 10%.

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