Ablation-resistant connector and method of making same

Abstract

The present application belongs to the technical field of high-temperature refractory composite material, and discloses a kind of ablation-resistant connecting piece and preparation method thereof.The ablation-resistant connecting piece includes a main connecting part of high-temperature alloy material and an ablation-resistant fixing part.The fixing part effectively protects the internal main connecting part by having ablation resistance and heat resistance.The main connecting part is processed by high-temperature alloy, which has high high-temperature strength.The fixing part is co-solidified with a high-temperature resistant adhesive on the main connecting part, and the bonding strength of the fixing part and the main connecting part is further improved by the embedded structure, so that the ablation-resistant connecting piece has both the heat resistance of ablation-resistant material and the high-temperature strength of high-temperature metal, and is suitable for connecting short-time high-speed aircraft.The preparation method of the ablation-resistant connecting piece requires relatively simple equipment, is convenient to operate, has stable process, high production efficiency, and is suitable for large-scale industrial production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-temperature refractory composite materials, and particularly relates to an ablation-resistant connecting piece and a preparation method thereof. BACKGROUND

[0002] During high-speed flight of a hypersonic aircraft, a large amount of heat is generated by friction with the atmosphere, so that the temperature of the nose cone, leading edge and other parts of the aircraft reaches 1800 DEG C. The screws used for connecting the structure of the thermal protection system need to withstand high temperature, high pressure and vibration, and therefore high-temperature strength and ablation resistance are required for the screws.

[0003] In the prior art, a C / SiC ceramic matrix composite screw is a commonly used high-temperature and ablation-resistant connecting screw for a hypersonic aircraft. The C / SiC ceramic matrix composite belongs to a carbon fiber reinforced ceramic matrix composite material, and has the advantages of high-temperature resistance, ablation resistance and oxidation resistance. Due to the characteristic that the strength of carbon fiber is higher at high temperature than at room temperature, the high-temperature strength of the ceramic matrix composite is superior to that at room temperature, and the tensile strength at 1200 DEG C. can reach 200-400 Ma. The preparation process of the C / SiC ceramic matrix composite is complex, and the carbon fiber needs to be protected by an interface, and then a costly ceramic precursor (not less than 2000 yuan per kilogram) is used for ten or more rounds of impregnation and high-temperature pyrolysis. The forming cycle of the C / SiC ceramic matrix composite generally needs 3-6 months, and the forming cycle of the material is long, and the cost is very high. SUMMARY

[0004] Therefore, the purpose of the application is to provide an ablation-resistant connecting piece and a preparation method thereof, so as to solve the problems of high cost, long cycle and complex preparation process of the connecting piece of the existing aircraft.

[0005] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the application:

[0006] On the one hand, an ablation-resistant connecting piece is provided, which comprises:

[0007] a main connecting part made of a high-temperature alloy material;

[0008] a fixing part made of a resin-based composite material I; and

[0009] The fixing part is bonded on the main connecting part by a bonding agent, the fixing part and the bonding agent are co-cured and formed on the main connecting part, and the bonding agent is made of a resin-based composite material II; and the connecting interface between the main connecting part and the fixing part is provided with a fitting structure.

[0010] In the possible implementation mode, the resin-based composite material I comprises a phenolic resin and a reinforcing material, and the reinforcing material comprises a chopped fiber material.

[0011] In a possible implementation, the short-cut fiber material is one of a short-cut high-silica fiber, a short-cut quartz fiber, and a short-cut carbon fiber.

[0012] In a possible implementation, the resin-based composite material II includes a phenolic resin, SiC fibers, ZrSi2 powder, and a silane coupling agent, and the weight ratio of the phenolic resin, SiC fibers, ZrSi2 powder, and silane coupling agent is 100: (10-20): (100-200): (1-6).

[0013] In a possible implementation, the content of glue of the phenolic resin is greater than or equal to 80%, the length of the SiC fiber is 0.5-2 mm, the purity of the ZrSi2 powder is greater than 99%, and the diameter of the ZrSi2 powder is 1-10 microns.

[0014] In a possible implementation, the fitting structure includes a fitting groove arranged on one of the connecting surface of the main body connecting part and the connecting surface of the fixing part, and a fitting protrusion arranged on the other of the connecting surface of the main body connecting part and the connecting surface of the fixing part, the fitting groove is formed by a plurality of grooves intersecting and penetrating through, and the fitting protrusion is matched with the fitting groove.

[0015] On the other hand, a preparation method of the ablation-resistant connecting piece is also provided, including the following steps:

[0016] A forming mold is provided, and the forming mold has a forming mold cavity matched with the ablation-resistant connecting piece;

[0017] A high-temperature alloy material is used to manufacture the main body connecting part of the ablation-resistant connecting piece, and a connecting structure for fitting is processed on the connecting surface of the main body connecting part;

[0018] The main body connecting part is installed in the corresponding part of the forming mold cavity, and then a coupling agent and a bonding agent made of the resin-based composite material II are coated on the connecting surface of the main body connecting part in sequence, and then a prepreg made of the resin-based composite material I is coated;

[0019] The materials in the internal forming mold cavity are solidified and formed by heating through the forming mold, the bonding agent and the prepreg are solidified and formed on the main body connecting part together, and the fixing part of the ablation-resistant connecting piece is formed;

[0020] The ablation-resistant connecting piece is taken out after the mold is removed.

[0021] In a possible implementation, the preparation method of the bonding agent includes:

[0022] The phenolic resin, SiC fiber, ZrSi2 powder and silane coupling agent are mixed and stirred uniformly according to the weight ratio of 100: (10-20): (100-200): (1-6) to obtain a binder, wherein the content of the phenolic resin is greater than or equal to 80%, the length of the SiC fiber is 0.5-2 mm, the purity of the ZrSi2 powder is greater than 99% and the diameter is 1-10 microns.

[0023] In a possible implementation, the method for preparing the prepreg comprises:

[0024] The short-cut fiber material is fully impregnated with the phenolic resin to obtain a prepreg, wherein the weight ratio of the short-cut fiber material to the phenolic resin is (40-80):(20-60).

[0025] In a possible implementation, the material in the inner molding cavity is cured and formed by heating through a molding die, including the following method:

[0026] The molding die is preheated to 70-100 DEG C and kept for 1-3 h;

[0027] The molding cavity is vacuumized, and the vacuum degree is less than or equal to -0.09, and the vacuumizing time is 1-2 h;

[0028] The molding die is heated, the heating temperature of the molding die is 70-100 DEG C and kept for 3-5 h, and then slowly heated to 150-170 DEG C and kept for 7-9 h.

[0029] In a possible implementation, before the coupling agent is coated on the connecting surface of the main body connecting part in sequence, the following steps are further included:

[0030] The surface where the connecting structure is located on the main body connecting part is subjected to sand blasting treatment, the sand blasting pressure is 0.1-1 MPa, and the distance between the sand blasting outlet and the metal sand blasting surface is 0.1-0.5 m.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] The ablation-resistant connecting piece comprises a main body connecting part made of a high-temperature alloy material and an ablation-resistant fixing part, the fixing part can effectively protect the main body connecting part inside through ablation resistance and heat resistance, the main body connecting part is processed by using a high-temperature alloy, the high-temperature strength is high, and the fixing part is co-cured and formed on the main body connecting part by using a high-temperature-resistant adhesive, so that the ablation-resistant connecting piece has the heat resistance of the ablation-resistant material and the high-temperature strength of the high-temperature metal, is suitable for the connection of a short-time high-speed aircraft, and the bonding strength of the fixing part and the main body connecting part can be further improved through the embedded structure.

[0033] The preparation method of the ablation-resistant connecting piece has the advantages of relatively simple required equipment, convenient operation, stable process, high production efficiency, suitability for large-scale industrialized production, and the like. Through the pre-impregnated material molding link of the fixing part, the measure of vacuumizing is added, the porosity of the resin-based composite material of the fixing part is reduced, and the ablation performance of the material is improved. The ablation-resistant connecting piece prepared by the method is not only suitable for the connection of short-time high-speed aircraft, but also can be used for the connection of missiles and rocket launching devices. Compared with the preparation process of the C / SiC ceramic matrix composite screw, the preparation method has the advantages of simple process, low cost, more than 95% reduction of the forming cycle, and more than 90% reduction of the cost. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a perspective view of an ablation-resistant connecting piece;

[0035] Figure 2 It is an exploded view of an ablation-resistant connecting piece;

[0036] Figure 3 It is a process flow diagram of a preparation method of an ablation-resistant connecting piece;

[0037] Figure 4 It is a split schematic view of an ablation-resistant connecting piece and a forming mold in a preparation method of an ablation-resistant connecting piece;

[0038] Figure 5 It is an assembly schematic view of an ablation-resistant connecting piece and a forming mold in a preparation method of an ablation-resistant connecting piece;

[0039] Figure 6 It is a position relationship diagram of an ablation sample and an engine in a preparation method of an ablation-resistant connecting piece;

[0040] Figure 7 It is a contrast diagram of appearances after ablation of Example 1 and Comparative Example 3 in a preparation method of an ablation-resistant connecting piece, wherein the left diagram is Example 1, and the right diagram is Example 3.

[0041] In the figure: 1-ablation-resistant connecting piece; 11-main body connecting part; 12-fixing part; 13-connecting groove; 14-embedded structure; 2-forming mold; 21-upper cover plate; 22-left half mold; 23-right half mold; 3-kerosene engine; 4-ablation sample. DETAILED DESCRIPTION

[0042] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with specific embodiments.

[0043] Please refer to Figure 1 and Figure 2As shown, the embodiment of the present application provides an ablation-resistant connecting piece 1, comprising: a main connecting part 11 made of high-temperature alloy material; a fixing part 12 made of resin-based composite material; wherein the fixing part 12 is bonded on the main connecting part 11 by an adhesive, the fixing part 12 and the adhesive are co-cured on the main connecting part 11, and the adhesive is made of resin-based composite material No. 2; and a fitting structure 14 is arranged at the connecting interface between the main connecting part 11 and the fixing part 12.

[0044] The ablation-resistant connecting piece 1 is a high-temperature-resistant and fire-resistant connecting piece, which can be used for fastening connection in special operation or extreme environment, such as connection of short-time high-speed aircraft, and can also be used for connection of missile and rocket launching device. The ablation-resistant connecting piece 1 mainly comprises the main connecting part 11 and the fixing part 12, the main connecting part 11 is the main part of the ablation-resistant connecting piece 1 for connecting target parts, and the fixing part 12 is used for locking and fixing the ablation-resistant connecting piece 1; the structure of the ablation-resistant connecting piece 1 can be various, such as screw structure or bolt structure, or clamping structure, or other connection structure forms of the main connecting part 11, which is not limited.

[0045] The main connecting part 11 is made of high-temperature alloy material, which is a metal material taking iron (Fe), nickel (Ni) and cobalt (Co) as matrix and capable of working at high temperature above 600℃ and stress environment for a long time, and the tensile strength of the high-temperature alloy at 1200℃ can reach more than 400MPa. The high-temperature strength of the high-temperature alloy has obvious advantages, but the melting point of the high-temperature alloy is generally not more than 1400℃, and the ablation-resistant ability of the high-temperature alloy is poor. In order to utilize the high strength of the high-temperature alloy and overcome the shortcomings thereof, the fixing part 12 made of resin-based composite material and the adhesive are co-cured on the main connecting part 11 made of high-temperature alloy material, the resin-based composite material has the advantage of good high-temperature heat-proof performance, and through the connecting action of the adhesive also made of resin-based composite material under the fitting structure 14, the bonding strength of the fixing part 12 and the main connecting part 11 can be improved to ensure the connection reliability of the connecting interface, and the high-temperature resistance can be realized, so that the advantages of high-temperature strength of the high-temperature alloy and good high-temperature heat-proof performance of the ablation-resistant resin-based composite material can be combined together, and the high-temperature protection of the main connecting part 11 by the fixing part 12 can overcome the disadvantage of poor ablation-resistant ability of the high-temperature alloy.

[0046] It can be understood that the resin-based composite material is a composite material formed by using resin material as a matrix and combining with a reinforcing material. Such a composite material has high strength and rigidity, and also has excellent heat resistance and flame resistance. In this way, the fixing part 12 made of the resin-based composite material 1 has the performance of resisting ablation, and the adhesive made of the resin-based composite material 2 has the performance of resisting high temperature and high strength, thereby ensuring that the main body connecting part 11 and the fixing part 12 can not easily fall off and can be reliably bonded in a high-temperature and vibration environment, and can effectively protect the main body connecting part 11. The adhesive, which is also a resin-based composite material, can play a connecting role. The adhesive and the matrix resin of the composite material are of the same type (such as both being epoxy resin or phenolic resin), and the active groups (such as epoxy groups and hydroxyl groups) thereof can directly participate in interfacial reaction to form a covalent bond network. In this way, the adhesive can ensure that it has high strength and connection reliability while resisting high temperature.

[0047] Through the above technical solution, the ablation-resistant connecting piece 1 includes the main body connecting part 11 made of high-temperature alloy material and the fixing part 12 that can effectively protect the internal main body connecting part 11 by having ablation resistance and heat resistance. The main body connecting part 11 is processed by using high-temperature alloy, which has high high-temperature strength. The fixing part 12 and the main body connecting part 11 are connected by using the high-temperature-resistant adhesive, so that the ablation-resistant connecting piece 1 has the heat resistance of the ablation-resistant material and the high-temperature strength of the high-temperature metal. The ablation-resistant connecting piece 1 is suitable for connecting short-time high-speed aircrafts, and the fitting structure 14 can further improve the bonding strength of the fixing part 12 and the main body connecting part 11.

[0048] In an embodiment, the resin-based composite material 1 includes phenolic resin and a reinforcing material, and the reinforcing material includes short-cut fiber material.

[0049] The resin-based composite material 1 uses phenolic resin as a matrix and short-cut fiber material as a reinforcing phase. The phenolic resin can inhibit high-temperature deformation of the phenolic resin by adding the short-cut fiber material. The short-cut fiber forms a three-dimensional network structure to disperse thermal stress and avoid brittle fracture of the matrix at high temperature. In this way, the fixing part 12 after forming can have high strength and high-temperature resistance, and can better protect the main body connecting part 11. The resin-based composite material 1 is made by using a conventional method, that is, the phenolic resin and the short-cut fiber material are fully infiltrated to form a material for curing and forming the fixing part 12. The resin-based composite material 1 is convenient to make and has low cost. The short-cut fiber material is one of short-cut high-silica fiber, short-cut quartz fiber, and short-cut carbon fiber.

[0050] In a preferred embodiment of the resin-based composite material 2, the resin-based composite material 2 includes phenolic resin, SiC fiber, ZrSi2 powder, and silane coupling agent, and the weight ratio of the phenolic resin, the SiC fiber, the ZrSi2 powder, and the silane coupling agent is 100: (10-20): (100-200): (1-6).

[0051] The resin matrix of the resin matrix composite two is the same as that of the resin matrix composite one, i.e. phenolic resin, which can be easily connected with the resin matrix composite one; the SiC fiber can provide excellent strength, stiffness and toughness, and prevent brittle fracture of the formed connecting interface; the ZrSi2 powder can react with the carbon product produced by the carbonization reaction of the phenolic resin at high temperature, especially in the high-temperature environment of the flight operation of the aircraft, under high temperature (usually higher than 1400°C). The reaction is not completed in one step, and ZrSi2 itself will also decompose at high temperature. The zirconium (Zr) and silicon (Si) decomposed will immediately react with the surrounding carbon, and then silicon carbide and zirconium carbide can be generated to form a composite ceramic material in a polycrystalline ceramic phase state. Since the melting points of silicon carbide and zirconium carbide are higher than the high-temperature environment of the aircraft flight, the overall high-temperature resistance, strength and anti-oxidation and anti-ablation performance can be improved. One end of the silane coupling agent is combined with the surface of the inorganic material (SiC fiber, ZrSi2 powder), and the other end is combined with the organic material (phenolic resin). The interface adhesion between the two originally incompatible phases is improved. The high-temperature cracking of the silane coupling agent generates a Si-O-Si network, promotes the chemical bonding of ZrSi2 / SiC and resin carbon, and inhibits interface cracking, thereby significantly improving the overall mechanical properties and environmental durability of the composite material.

[0052] Preferably, the content of the phenolic resin is ≥80%, the length of the SiC fiber is 0.5-2 mm, and the purity of the ZrSi2 powder is greater than 99% and the diameter is 1-10 microns. The content of the phenolic resin greater than 80% can play a role in fully infiltrating and bonding continuity during the production process of the SiC fiber, and a more three-dimensional cross-linked structure can be formed after curing. If the SiC fiber is too short (<0.5 mm), the reinforcing effect will be weak, and if it is too long (>2 mm), it will be easy to agglomerate. However, the use of a length range of 0.5-2 mm can improve the bending strength and optimize the mixing flowability to avoid uneven orientation. High-purity ZrSi2 powder can avoid the formation of low-melting-point phases by impurities (such as Fe and Al), ensuring the density of the protective layer. If the particle size is too fine (<1 μm), it will be easy to oxidize in advance, and if it is too coarse (>10 μm), it will be unevenly dispersed. The use of powder of this size can achieve uniform dispersion and controllable reaction rate.

[0053] In some application scenarios, the ablation-resistant connecting piece 1 is preferably a screw structure, which can be used for connecting short-time high-speed aircrafts, and can also be used for connecting missiles and rocket launchers.

[0054] Please refer to Figure 3-5 The embodiment of the present application also provides a preparation method of the ablation-resistant connecting piece 1, which comprises the following steps:

[0055] Step S100: providing a molding die 2, which has a molding cavity matching the ablation-resistant connecting piece 1.

[0056] In this step, the molding cavity of the molding die 2 is used to mold the ablation-resistant connecting piece 1, which also has a cavity one corresponding to the fixed part 12 and a cavity two corresponding to the main body connecting part 11 of the ablation-resistant connecting piece 1, and the resin-based composite material one and the resin-based composite material two can be cured and molded into the fixed part 12 in the cavity one and connected with the main body connecting part 11. In the specific implementation process, the molding die 2 includes three parts of a left half die 22, a right half die 23, and an upper cover plate 21, the left half die 22 and the right half die 23 are connected by screws, and the upper cover plate 21 is connected with the left half die 22 and the right half die 23 by screws, and the molding cavity formed after the left half die 22, the right half die 23, and the upper cover plate 21 are connected by screws is consistent with the shape of the ablation-resistant screw. The left half die 22, the right half die 23, and the upper cover plate 21 are all arranged with a channel with a diameter of 2 mm for vacuumizing.

[0057] Step S200: using a high-temperature alloy material to make the main body connecting part 11 of the ablation-resistant connecting piece 1, and processing a connecting structure for embedding on the connecting surface of the main body connecting part 11.

[0058] In this step, the main body connecting part 11 is made of a high-temperature alloy material, and a connecting structure for embedding is processed on the connecting surface for connecting with the fixed part 12, which can be a groove structure or a protruding structure, so that the resin-based composite material one and the resin-based composite material two as an adhesive can fill or cover the connecting structure in the molding cavity to form a matching and embedding structure, thereby improving the connection reliability and bonding strength of the resin-based composite material one connected to the main body connecting part 11 by the adhesive.

[0059] Step S300: loading the main body connecting part 11 into the corresponding part of the molding cavity of the molding die 2, and then coating a coupling agent and an adhesive made of the resin-based composite material two on the connecting surface of the main body connecting part 11 in sequence, and then laying a prepreg made of the resin-based composite material one.

[0060] In this step, the main body connecting part 11 is loaded into the corresponding part of the molding cavity after being processed, and then a coupling agent is coated on the connecting surface of the main body connecting part 11, which can be a silane coupling agent, and after the coating is completed, the room temperature is placed for 1 h, and then an adhesive made of the resin-based composite material two is coated, and finally a prepreg made of the resin-based composite material one for molding the fixed part 12 is laid.

[0061] Step S400: The material in the inner molding cavity is solidified and molded by heating through the molding die 2, and the binder and the prepreg are solidified and molded together on the main body connecting part 11 and are formed into the fixed part 12 of the ablation-resistant connecting piece 1, respectively.

[0062] In this step, the coupling agent, the binder and the prepreg in the molding cavity are solidified and molded together by heating. Since the material in liquid or fluid state before solidification can fill or cover the connecting structure on the main body connecting part 11 for fitting, the fitting structure 14 with improved connecting reliability can be formed after solidification, and the coupling agent, the binder and the prepreg can be connected by solidification together, so that the ablation-resistant connecting piece 1 with high strength and connecting reliability can be ensured while being resistant to high temperature. The prepreg after solidification and molding is the fixed part 12 of the ablation-resistant connecting piece 1. It can be understood that since the binder and the prepreg are both resin-based composite materials, there is no obvious delamination in the structure and shape. The connecting groove 13 for connecting and dismounting tools is also formed on the fixed part 12.

[0063] Step S500: The ablation-resistant connecting piece 1 is taken out after the mold is removed.

[0064] In this step, the ablation-resistant connecting piece 1 is obtained after the mold is removed after natural cooling of the molding die 2 after solidification and molding.

[0065] Through the above technical solution, the required equipment is relatively simple, the operation is convenient, the process is stable, the production efficiency is high, and it is suitable for large-scale industrial production. Compared with the preparation process of the C / SiC ceramic-based composite material screw, the preparation method has simple process, low cost, and the molding cycle can be reduced by more than 95%, and the cost can be reduced by more than 90%.

[0066] In an embodiment, the preparation method of the binder comprises:

[0067] The phenolic resin, SiC fiber, ZrSi2 powder and silane coupling agent are mixed and stirred uniformly according to the weight ratio of 100: (10-20): (100-200): (1-6) to obtain the binder, wherein the content of the phenolic resin is ≥80%, the length of the SiC fiber is 0.5-2mm, the purity of the ZrSi2 powder is greater than 99% and the diameter is 1-10 microns.

[0068] In this way, the SiC fiber can provide excellent strength, stiffness and toughness, prevent the formed connecting interface from brittle fracture; the ZrSi2 powder can react with oxygen to form a silica glass layer at high temperature, especially in the high temperature environment of the aircraft flight operation, which can effectively block the crack and prevent the inward diffusion of oxygen, thereby providing the connecting interface with oxidation resistance and ablation resistance; the one end of the silane coupling agent is combined with the surface of the inorganic matter (SiC fiber, ZrSi2 powder), and the other end is combined with the organic matter (phenolic resin), which improves the interfacial adhesion between the two originally incompatible phases, thereby significantly improving the overall mechanical properties and environmental durability of the composite material. The phenolic resin has a glue content of ≥80%, the length of the SiC fiber is 0.5-2mm, and the purity of the ZrSi2 powder is greater than 99% and the diameter is 1-10 microns, which can improve the comprehensive connection performance of the adhesive after curing.

[0069] Further, the preparation method of the prepreg comprises:

[0070] The short fiber material is fully infiltrated with the phenolic resin to obtain a prepreg, wherein the weight ratio of the short fiber material to the phenolic resin is (40-80):(20-60).

[0071] The prepreg has a phenolic resin as a matrix and a short fiber material as a reinforcing phase. The phenolic resin can inhibit high temperature deformation of the phenolic resin by adding the short fiber material. The short fiber forms a three-dimensional network structure to disperse thermal stress and avoid high temperature brittle fracture of the matrix. Thus, the fixed part 12 after forming can have high strength and high temperature resistance, better protecting the main connecting part 11. The resin matrix composite is made by a conventional method, i.e. the phenolic resin is fully infiltrated with the short fiber material to form a material for curing and forming the fixed part 12, which is convenient and low in cost.

[0072] In order to reduce the porosity of the resin matrix composite during the forming process, in step S400, the material in the internal forming mold cavity is cured and formed by heating the forming mold 2, including the following methods:

[0073] Step S410: preheat the forming mold 2 to 70-100°C and keep warm for 1-3h;

[0074] Step S420: vacuumize the forming mold cavity, the vacuum degree is ≤-0.09, and the vacuumizing time is 1-2h;

[0075] Step S430: heat the forming mold 2, the heating temperature of the forming mold 2 is 70-100°C and keep warm for 3-5h, then slowly heat to 150-170°C and keep warm for 7-9h.

[0076] In this way, by the measure of vacuumizing, the porosity of the screw head composite material is reduced, and the ablation performance of the material is improved.

[0077] In the implementation process, before the coupling agent is coated on the connecting surface of the main body connecting part 11, the following steps are further included: sandblasting the surface on which the connecting structure of the main body connecting part 11 is located, the sandblasting pressure is 0.1-1 MPa, and the distance between the sandblasting outlet and the metal sandblasting surface is 0.1-0.5 m. By sandblasting the connecting surface of the main body connecting part 11, the adhesion of the coupling agent, the adhesive and the prepreg on the connecting surface can be further improved.

[0078] The application will be further described below by means of specific examples. The ablation-resistant connecting parts in the following specific examples are screw structures, and the screws are used as the main body connecting parts, and the fixing parts are the screw heads combined with the screws.

[0079] Example 1:

[0080] A screw body used as the main body connecting part is processed by using a nickel-based high-temperature alloy. The surface of the screw body is an M8 thread. There are four grooves with a depth of 1 mm at the position connected with the screw head.

[0081] 65% of chopped quartz fibers with a length of 1 mm and 35% of phenolic resin are fully mixed and infiltrated to obtain a chopped quartz fiber phenolic prepreg.

[0082] The phenolic resin, SiC fibers, ZrSi2 powder, powder and silane coupling agent (KH-550) are uniformly mixed and stirred to obtain an adhesive. The weight ratio of the phenolic resin, SiC fibers, ZrSi2 powder and silane coupling agent (KH-550) is 100:15:150:4. The adhesive content of the phenolic resin is 85%, the length of the SiC fibers is 1 mm, the purity of the ZrSi2 is 99.2%, and the diameter is 1 micrometer.

[0083] The surface of the forming mold is cleaned before use, and release agent is applied 3 times. After each application, it is left to stand for 30 min. The surface of the groove is sandblasted, the sandblasting pressure is 0.5 MPa, the distance between the sandblasting outlet and the metal sandblasting surface is 0.25 m, and the next step is performed within 2 h after sandblasting.

[0084] The screw body of the high-strength metal is screwed into the M8 screw hole formed by the left half mold 22 and the right half mold 23 of the forming mold 2, and then the silane coupling agent KH-550 is applied to the sandblasted area. After standing at room temperature for 1 h, the prepared adhesive is applied, and finally the chopped fiber phenolic prepreg for screw head forming is laid.

[0085] The forming mold 2 is preheated to 85°C and kept for 1 h. The upper cover plate 21 is installed on the left half mold 22 and the right half mold 23 through fasteners. During the installation process, the mold cavity is evacuated through the channel of the left half mold 22, the right half mold 23 and the upper cover plate 21, the vacuum degree is -0.08, and the time is 1.5 h.

[0086] Stop vacuum, mold heating and curing, mold temperature 90℃, keep warm 4h, slowly warm up to 160℃, keep warm 8h.

[0087] Mold natural cooling, demolding, get the ablation-resistant screw.

[0088] Example 2:

[0089] The screw body as the main connecting part is processed by nickel-based superalloy, the surface of the screw body is M8 thread, and the part connected with the screw head has 4 grooves with a depth of 1mm;

[0090] Mix and infiltrate 76% chopped quartz fiber with a fiber length of 1mm and 24% phenolic resin to obtain a chopped quartz fiber phenolic prepreg;

[0091] Mix and stir the phenolic resin, SiC fiber, ZrSi2 powder, and silane coupling agent (KH-550) uniformly to obtain the adhesive, wherein the weight ratio of phenolic resin: SiC fiber: ZrSi2 powder: silane coupling agent (KH-550) = 100: 11: 112: 2; the glue content of the phenolic resin is 86%, the length of the SiC fiber is 0.6mm, the purity of ZrSi2 is 99.3%, and the diameter is 2 microns;

[0092] Clean the surface of the forming mold before use, apply release agent 3 times, and air dry for 30 minutes after each application. Sandblast the surface where the grooves are located, the sandblast pressure is 0.2MPa, the distance between the sandblast outlet and the metal sandblast surface is 0.15m, and the next step is performed within 2h after sandblasting;

[0093] Twist the screw body of high-strength metal into the M8 screw hole formed by the left half mold 22 and the right half mold 23 of the forming mold 2, then apply silane coupling agent KH-550 to the sandblasted area, and after 1h at room temperature, apply the prepared adhesive, and finally lay the chopped fiber phenolic prepreg for screw head forming;

[0094] Preheat the forming mold 2 to 73℃ and keep warm for 1.2h. Install the upper cover plate 21 to the left half mold 22 and the right half mold 23 through fasteners. During the installation process, start vacuumizing the mold cavity through the channel of the left half mold 22, the right half mold 23, and the upper cover plate 21. The vacuum degree is -0.09, and the time is 1.5h.

[0095] Stop vacuum, mold heating and curing, mold temperature 75℃, keep warm 4.5h, slowly warm up to 156℃, keep warm 8.5h.

[0096] Mold natural cooling, demolding, get the ablation-resistant screw.

[0097] Example 3:

[0098] The screw body as the main connecting part is made of nickel-based high-temperature alloy, the surface of the screw body is M8 thread, and the part connected with the screw head has four grooves with a depth of 1 mm;

[0099] The chopped quartz fiber with a length of 1 mm and the phenolic resin are fully mixed and infiltrated to obtain the chopped quartz fiber phenolic prepreg.

[0100] The phenolic resin, SiC fiber, ZrSi2 powder, silane coupling agent (KH-550) are mixed and stirred uniformly to obtain the adhesive, wherein the weight ratio of the phenolic resin: SiC fiber: ZrSi2 powder: silane coupling agent (KH-550) is 100:18:195:5; the glue content of the phenolic resin is 89%, the length of the SiC fiber is 0.5 mm, the purity of the ZrSi2 is 99.2%, and the diameter is 1 micrometer;

[0101] The surface of the forming mold is cleaned before use, and release agent is applied 3 times, and each time after applying, it is placed for 30 min, and the surface where the groove is located is sandblasted, the sandblasting pressure is 0.7 MPa, the distance between the sandblasting outlet and the metal sandblasting surface is 0.45 m, and the next step is carried out within 2 h after sandblasting;

[0102] The screw body of high-strength metal is screwed into the M8 screw hole formed by the left half mold 22 and the right half mold 23 of the forming mold 2, then the sandblasted area is coated with silane coupling agent KH-550, and after being placed at room temperature for 1 h, the prepared adhesive is coated, and finally the chopped fiber phenolic prepreg for screw head forming is laid;

[0103] The forming mold 2 is preheated to 90 DEG C, and the upper cover plate 21 is installed on the left half mold 22 and the right half mold 23 by fastening, and during the installation process, the mold cavity is vacuumized through the channel of the left half mold 22, the right half mold 23 and the upper cover plate 21, the vacuum degree is-0.09, and the time is 1.7 h;

[0104] Stop vacuumizing, heat and cure the mold, the mold temperature is 90 DEG C, the temperature is kept for 4 h, and then slowly heated to 165 DEG C, and kept for 8 h.

[0105] The mold is naturally cooled, and the mold is removed to obtain the ablation-resistant screw.

[0106] In order to better illustrate the performance of the embodiments of the application, comparative examples 1-4 are provided as a comparison.

[0107] Comparative example 1:

[0108] The screw body was made of nickel-based superalloy, and the screw head was made of chopped quartz fiber phenolic prepreg with a fiber length of 1 mm. The high-temperature adhesive was obtained by uniformly mixing and stirring phenolic resin, SiC fiber, ZrSi2 powder, and silane coupling agent (KH-550). The weight ratio of phenolic resin: SiC fiber: ZrSi2 powder: silane coupling agent (KH-550) was 100:3:150:4. The glue content of the phenolic resin was 85%. The length of the SiC fiber was 1 mm. The purity of ZrSi2 was 99.2%, and the diameter was 1 micrometer.

[0109] The difference between the screw forming method described in Example 1 is that no groove is processed at the connection part of the screw head. The other steps are the same as in Example 1.

[0110] Comparative Example 2:

[0111] Compared with the materials used in Example 1, the screw body was made of nickel-based superalloy, and the screw head was made of chopped quartz fiber phenolic prepreg. No high-temperature adhesive was used at the connection between the screw head and the screw body.

[0112] The difference between the screw forming method described in Example 1 is that no high-temperature adhesive is used at the connection between the screw head and the screw body. The other steps are the same as in Example 1.

[0113] Comparative Example 3:

[0114] Compared with the materials used in Example 1, the screw body was made of nickel-based superalloy, and the screw head was made of chopped quartz fiber phenolic prepreg. The composition of the high-temperature adhesive was the same as in Example 1.

[0115] The difference between the screw forming method described in Example 1 is that no vacuum is applied to the mold during installation. The other steps are the same as in Example 1.

[0116] Comparative Example 4:

[0117] Compared with the screw body material used in Example 1, the screw body was made of nickel-based superalloy. The screw head was not made of chopped quartz fiber phenolic prepreg, but was made of quartz fiber cloth phenolic prepreg. The high-temperature adhesive was obtained by uniformly mixing and stirring phenolic resin, SiC fiber, ZrSi2 powder, and silane coupling agent (KH-550). The weight ratio of phenolic resin: SiC fiber: ZrSi2 powder: silane coupling agent (KH-550) was 100:12:300:4. The glue content of the phenolic resin was 88%. The length of the SiC fiber was 0.5 mm. The purity of ZrSi2 was 99.6%, and the diameter was 3 micrometers.

[0118] The difference between the screw forming method described in Example 1 and the screw forming method described in Example 2 is that the chopped fiber phenolic prepreg for forming the ablation-resistant screw head is replaced by a quartz fiber cloth phenolic prepreg. The other steps are the same as those in Example 1.

[0119] The screws prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to high-temperature gas flow ablation test. Specifically, an ablation-resistant flat plate with a size of 120mm*200*10mm was processed, and a screw hole with M6 was processed at a fixed position on the flat plate. The prepared screw was screwed into the screw hole, the top of the ablation-resistant screw was flush with the surface of the ablation-resistant flat plate, and finally the ablation-resistant sample 4 was subjected to high-temperature gas flow ablation using a kerosene engine 3. The combustion chamber pressure was 0.8MPa, the gas flow temperature was 1800-2000℃, the ablation time was 10s, and the positional relationship between the ablation-resistant sample 4 and the engine is shown in Figure 6 .

[0120] Based on the above high-temperature gas flow ablation test, the performance test results of the screws prepared in Examples 1-3 and Comparative Examples 1-4 are shown in Table 1 below. The shear strength is the test data of the adhesive at a temperature of 1500℃, and the test standard is GB / T7124-2008:

[0121] Table 1

[0122]

[0123] The high-temperature gas flow ablation test results of the screws prepared in Examples 1-3 and Comparative Examples 1-4 are as follows:

[0124] 1. At a test time of 2s, the screw heads of Comparative Example 1, Comparative Example 2 and Comparative Example 4 fell off from the screw body and the ablation test was not completed.

[0125] 2. Examples 1-3 and Comparative Example 3 completed the ablation test. The screw heads of Examples 1-3 had excellent ablation performance, no obvious ablation amount, reliable adhesion between the screw head and the screw body, and protected the screw body. The screw head of Comparative Example 3 had relatively poor ablation performance, and the screw body leaked locally, which had relatively poor protection effect on the screw body. Figure 7 The ablation effects of the screws of Example 1 and Comparative Example 3 are as follows:

[0126] 3. As can be seen from Table 1, the high-temperature shear strength of the adhesive prepared by the preparation method of Examples 1-3 is significantly higher than that of Comparative Examples 1 and 4.

[0127] The high-temperature gas flow scouring ablation test results of the above-mentioned screws show that the screws of Examples 1-3 are structurally complete after ablation, the ablation amount of the screw head is small, the screw head and the screw body structure are well combined, the shear strength is higher, and the screws of Examples 1-3 are suitable for the connection of high-speed aircraft; in the preparation of the screw of Comparative Example 1, the groove connecting the screw body and the screw head is cancelled, the combined area and mechanical coupling of the two are reduced, and the screw head is easy to fall off from the screw body at high temperature; in the preparation of the screw of Comparative Example 2, the high-temperature adhesive between the screw body and the screw head is cancelled, and the screw body and the screw head are only bonded by phenolic resin, the initial decomposition temperature of the phenolic resin is not more than 300°C, when the temperature of the joint surface of the screw head and the screw body exceeds 300°C, the bonding strength of the screw head and the screw body decreases rapidly, and the screw head falls off from the screw body; in the preparation of the screw of Comparative Example 3, the vacuumizing treatment of the screw head during the mould pressing process is cancelled, the porosity of the screw head material is high, the ablation resistance of the material decreases, and local ablation and erosion problems occur, increasing the failure risk of the screw during use. In the preparation of the screw of Comparative Example 4, the mould pressing material of the screw head is changed from chopped fiber prepreg to fiber cloth prepreg, compared with the chopped fiber prepreg, the fiber cloth prepreg has poor deformation ability during mould pressing, cannot fit the groove of the screw body, reduces the combined area and mechanical coupling of the two, and the screw head is easy to fall off from the screw body at high temperature.

[0128] Through the above tests and analysis, the use of chopped fiber prepreg with strong deformation ability, the addition of grooves on the joint surface of the screw body and the screw head, the increase of the combined area and mechanical coupling force of the screw body and the screw head, and the further addition of adhesive-resistant material on the joint surface of the two can improve the high-temperature bonding strength of the two. The vacuumizing treatment during the mould pressing of the screw head can reduce the porosity of the screw head composite material and improve the ablation resistance of the screw head. The above structural design and forming process measures are the keys for the screw to be used on high-speed aircraft. At the same time, compared with the existing C / SiC ceramic matrix composite material, the forming cycle is ≤7 days, the cost is ≤200 yuan, and the comprehensive cost is reduced by more than 90%.

[0129] The ablation-resistant connecting piece of the present application uses inorganic fiber reinforced phenolic in the fixed part, and quartz fiber reinforced phenolic is generally preferred. The material belongs to a melting type ablation material, which can withstand a high temperature of about 2200°C. At this temperature, the resin decomposes and the fiber melts to consume heat, reducing the internal temperature of the material. When the temperature exceeds the melting point of the quartz fiber, the higher the temperature, the greater the linear ablation rate after the screw head falls off from the screw body. The use conditions of the ablation-resistant connecting piece of the present application are as follows: the inorganic fiber reinforced phenolic in the fixed part has a certain thickness, which ensures that the interface temperature of the fixed part and the main body connecting part during use does not exceed the use temperature of the adhesive connecting the two and the high-temperature alloy of the main body connecting part. At the same time, a suitable high-temperature alloy material is selected, and the thread size of the main body connecting piece is reasonably determined to ensure the high-temperature strength of the main body connecting part.

[0130] After high temperature test experiment of the fixed part material, the test piece made of the same material and preparation method as the fixed part of example 1 is used for two groups of ablation resistance tests, the thickness of the test pieces in each group is basically the same, and the center of the test piece is ablated, after the test, the ablation thickness of four measuring points at 40mm, 55mm, 70mm and 85mm from the ablation center of the test piece is measured, at the same time, the ablation depth, ablation rate and average ablation rate are calculated, it is found that at 2200℃, the linear ablation rate of the material is 0.1-0.2mm / s, the ablation surface temperature is about 2200℃, the linear ablation rate is 0.14mm / s; while the temperature exceeds 2200℃, the linear ablation rate of the material is too large, which is not recommended to use; when the temperature is lower than the melting point of quartz fiber 1650℃, the material fiber will not melt, and linear ablation recession will not occur. Please refer to table 2.

[0131] Table 2

[0132]

[0133] Therefore, the ablation-resistant connecting piece of the present application is suitable for short-time high-speed flight scenes, for example, for missile protection, the maximum surface temperature of the ablation-resistant connecting piece used in the outer surface of the ballistic missile and the ground launching device is generally 1600-2000℃, the time of the ballistic missile entering the atmosphere is generally not more than 100s, and the heat launching time of the ground launching device is not more than 1s, and the ablation-resistant connecting piece of the present application is suitable for all of them.

[0134] The above is only the preferred embodiment of the present application, it should be pointed out that the above preferred embodiment should not be regarded as the limitation of the present application, the protection scope of the present application should be limited by the scope defined by the claims. For ordinary skilled in the art, several improvements and refinements can be made without departing from the spirit and scope of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. An ablative-resistant connector, comprising: include: The main body connecting part is made of high-temperature alloy material; and A fixing part made of resin-based composite material; The fixing part is bonded to the main body connecting part by an adhesive, and the fixing part and the adhesive are co-cured on the main body connecting part. The adhesive is made of resin-based composite material. The connection interface between the main body connecting part and the fixing part is provided with an interlocking structure. The resin-based composite material comprises phenolic resin, SiC fiber, ZrSi2 powder and silane coupling agent, wherein the weight ratio of phenolic resin, SiC fiber, ZrSi2 powder and silane coupling agent is 100:(10-20):(100-200):(1-6). The resin-based composite material includes phenolic resin and reinforcing material, wherein the reinforcing material includes chopped fiber material.

2. A ablative joint as claimed in claim 1, wherein, The phenolic resin has a resin content of ≥80%, the SiC fiber length is 0.5-2mm, and the ZrSi2 powder purity is greater than 99% and the diameter is 1-10 micrometers.

3. An ablative joint as claimed in claim 1, wherein, The fitting structure includes a connecting groove on one of the connecting surfaces of the main body connecting part and the fixing part, and a connecting protrusion on the other of the connecting surfaces of the main body connecting part and the fixing part. The connecting groove is formed by several intersecting grooves, and the connecting protrusion matches the connecting groove.

4. A method of producing a heat-resistant connection according to any one of claims 1 to 3, characterized in that Includes the following steps: Provide molding dies with molding cavities that match the ablation-resistant connectors; The main connecting part of the ablation-resistant connector is made of high-temperature alloy material, and the connecting surface of the main connecting part is machined with a connecting structure for fitting. The main connecting part is inserted into the corresponding part of the molding cavity of the molding mold, and then the coupling agent and the adhesive made of resin-based composite material II are coated on the connecting surface of the main connecting part in sequence, and then the prepreg made of resin-based composite material I is covered on it. The material inside the molding cavity is cured by heating the molding mold. The adhesive and prepreg are cured together on the main body connection part and form a fixed part of the ablation resistant connector. Remove the ablation-resistant connector from the mold.

5. A method of making an ablative joint as claimed in claim 4, wherein, The method for preparing the adhesive includes: Phenolic resin, SiC fiber, ZrSi2 powder and silane coupling agent are mixed and stirred evenly in a weight ratio of 100:(10-20):(100-200):(1-6) to obtain an adhesive. The phenolic resin has a glue content of ≥80%, the SiC fiber has a length of 0.5-2 mm, and the ZrSi2 powder has a purity of greater than 99% and a diameter of 1-10 micrometers.

6. The method of claim 4, wherein the ablation-resistant connector is formed by the steps of: The method for preparing the prepreg includes: ​ Prepreg is obtained by fully impregnating chopped fiber material with phenolic resin, wherein the weight ratio of chopped fiber material to phenolic resin is (40-80):(20-60).

7. The method for preparing an ablation-resistant connector as described in claim 4, characterized in that, Heating a molding die to solidify the material within its cavity includes the following methods: Preheat the molding mold to 70-100℃ and keep it at that temperature for 1-3 hours; Vacuum the molding cavity to a vacuum level ≤ -0.09, and the evacuation time is 1-2 hours; Heat the molding mold to a temperature of 70-100℃ and hold for 3-5 hours, then slowly raise the temperature to 150-170℃ and hold for 7-9 hours.

8. The method of claim 4, wherein the ablation-resistant connector is formed by the steps of: Before the connecting surface of the main body connecting part is coated with the coupling agent in sequence, the following steps are further included: ​ The surface of the connecting structure on the main body connecting part is subjected to sand blasting treatment, the sand blasting pressure is 0.1-1MPa, and the distance between the sand blasting outlet and the metal sand blasting surface is 0.1-0.5m.

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