CN115958816A - A light-weight, low-ablation nozzle expansion section and its preparation method - Google Patents

Abstract

The invention provides a preparation method of a light and low ablation spray pipe expansion section, which comprises the steps of mixing high carbon residue phenolic resin, polyacrylonitrile-based chopped carbon fiber and a solvent in proportion to form a premix, after the premix is subjected to solvent removal treatment, filling the premix into an expansion section prefabricated part curing tool, heating and pressurizing the premix by a press to cure the premix into a prefabricated part blank, and adding the prefabricated part blank by a prefabricated part machine to obtain a prefabricated part; weaving the composite expansion section preform outside the preform and at the large end part of the expansion section by adopting a carbon cloth/net tire + needling forming process, impregnating phenolic resin after the preform is manufactured, heating and pressurizing the preform in an expansion section integral die pressing tool by a press to solidify the preform into a composite expansion section product, and locally machining the expansion section blank in the subsequent spray pipe production to be assembled with a spray pipe shell in place. The invention solves the problems of lower material strength, large ablation amount in a high-temperature and high-pressure working environment, heavier weight of the spray pipe and the like of the winding expansion section, and meets the requirement of the solid rocket engine on the performance of the spray pipe with high impact mass ratio.

Description

A light-weight, low-ablation nozzle expansion section and its preparation method

technical field

The invention relates to the field of solid rocket motor nozzles, in particular to a light-weight, low-ablation nozzle expansion section and a preparation method thereof.

Background technique

At present, most of the expansion section materials of the solid rocket motor nozzles produced in domestic batches are carbon cloth/high silica cloth reinforced phenolic resin composite winding products. The carbon cloth/high silica cloth reinforced phenolic resin composite winding expansion section has a large amount of ablation under high temperature and high pressure working environment, so it is necessary to increase the design thickness of the material to ensure the anti-ablation ability during the long-term scouring process, resulting in the expansion section often The negative mass is too large, which does not meet the requirements of the nozzle weight reduction index. Therefore, the expansion section with light weight, long-term low ablative performance has become an inevitable choice for advanced high-performance nozzles.

The existing technical schemes of light weight and low ablation expansion section mainly include: Patent CN111997781A adopts the composite material expansion section forming method based on the RTM process semi-cured surface to prepare the expansion end section of the double-layer composite material nozzle, wherein the inner layer is 2.5D carbon fiber fabric reinforced resin-based composite material ablation layer, the outer layer is a high-silica fiber cloth tape wound heat insulation layer. In the preparation method of the expansion section, the ablation layer prepared from the 2.5D carbon fiber prefabricated body, during the operation of the high-pressure engine, the burning surface of the warp and weft yarns exposed to the gas is different, which will cause different anti-ablation peeling ability, which is easy to cause Similar to the wavy ablation morphology, the ablation uniformity is poor, and this method involves RTM tooling design, tape winding technology, autoclave pressure curing and other molding technologies, and the molding process also requires different tooling. , resulting in a more complex process and many factors affecting product quality; Patent CN106116623A aims at the existing disadvantages of heavy weight and high cost of the diffusion section, using vapor deposition to impregnate carbon fiber fabrics, and then cracking to obtain C/C blanks. The blank is immersed in a xylene solution of polycarbosilane, and finally undergoes a series of operations of physical pressure curing, high temperature cracking and mechanical processing to obtain the expanded section of the required size. The preparation process requires the use of special equipment such as vapor deposition equipment and high-temperature cracking furnace, and the impregnation-curing-cracking process must be repeated 5-7 times to achieve the required product density. The whole process is complicated, the equipment requirements are high, and the process cost Higher; CN209011969U patent is based on the carbon cloth-high silicon oxide cloth/phenolic winding expansion section, and introduces a carbon/silicon carbide composite winding material with a small thickness and relatively light weight in the rear section of the expansion section to reduce the overall weight. In the final analysis, it is the winding expansion section. Compared with the needle-punched preform, the interlayer shear performance of the winding process composite material is poor, and the thin-walled structure design of the winding expansion section is prone to structural delamination after high-temperature carbonization.

Most of the existing expansion section materials are prepared by carbon cloth/high silica cloth reinforced phenolic resin composite winding technology, which mainly has the following two deficiencies in the actual engine application: one is the "step" effect of the small end of the expansion section (compared with the throat liner). Butt joint) is significant, and the ablation rate is large, which leads to a decrease in the specific impulse efficiency of the expansion section, and even causes structural damage to the expansion section; on the other hand, the outlet cone of the expansion section is a thin-walled structure, and the traditional winding process composite material has low interlayer performance. The problem is that structural delamination is prone to occur after high-temperature carbonization. In order to reduce the influence of the carbonization zone, it is necessary to adopt a design idea of increasing the wall thickness, but this situation will cause a significant increase in the negative mass of the expansion section.

Contents of the invention

One of the objectives of the present invention is to provide a light-weight, low-ablation nozzle expansion section, which solves the problem of low material strength in the existing winding expansion section, large ablation volume under high-temperature, high-pressure, and high-strength working environments, and requires a thicker winding thickness to meet Anti-ablation requirements lead to problems such as heavy nozzle weight, which meets the performance requirements of advanced solid rocket motors for high impulse-to-mass ratio nozzles.

In order to solve the above technical problems, the present invention provides a method for preparing a light-weight, low-ablation nozzle expansion section, including:

S1: Preparation of the small end of the expansion section: Mix the high-carbon residual phenolic resin, polyacrylonitrile-based chopped carbon fiber, and solvent in proportion to form a premix. After the premix is desolventized, put it into the curing tooling of the prefabricated part of the expansion section. After being heated and pressurized by the press, it is solidified into a prefabricated part blank, and the prefabricated part blank is machined to obtain a prefabricated part;

S2: Preparation of the large end of the expansion section: on the outer side of the preform and the large end of the expansion section, the composite expansion section prefabricated body is braided using carbon cloth/mesh tire + needle punching molding technology. After it is made, it is impregnated with phenolic resin. In the molding tooling, it is heated and pressurized by the press to be solidified into a composite expansion section product. The expansion section blank is partially machined in the subsequent nozzle production and assembled with the nozzle casing in place.

Further, industrial alcohol is used as the solvent in S1, wherein the mass ratio of high carbon residue phenolic resin, polyacrylonitrile-based chopped carbon fiber and solvent is 1:1.4-1.6:2.8-3.2.

Further, the premixed material in S1 is desolvated at 70-80° C. to keep the content of volatile component x in the premixed material at 3.0%≤x≤5.5%.

Further, the step of heating and curing in the S1 medium press is: raising the temperature from room temperature to 80-90°C within 50-60min and keeping it for 120-130min; then raising the temperature to 100-110°C within 50-60min and keeping it for 90-100min ;Finally, heat up to 170-180°C within 140-150min, and keep it for 150-160min; the pressing and curing steps of the press are: pressurize 1.0-1.5MPa at 80-90°C to close the mold; pressurize at 100-110°C at 3.0- 3.5MPa; when holding at 100-110°C for 60-70min, deflate for 1-2min and pressurize at 6.0-6.5MPa; when holding at 100-110°C for 90-100min, deflate for 1-2min and pressurize at 10.0-10.5 MPa, keep the pressure until the end of the program. After the curing is completed, the solidified tooling is naturally cooled to room temperature, and the small end preform is removed from the mold.

Further, the carbon cloth in S2 is T800 polyacrylonitrile-based carbon fiber twill cloth, and the mesh tire is T700 polyacrylonitrile-based carbon fiber, wherein, carbon cloth and carbon fiber mesh tires are alternately laminated, and the laying direction is the direction of the busbar of the expansion section. Parallel, the whole prefabricated body of the composite expansion section formed into a conical structure is fixed through the needle punching process.

Further, after the preform of the composite expansion section in S2 is press-molded, the preform is dehumidified under the condition of 105-110°C/2h.

Further, the step of heating and curing in the S2 medium press is: heating from room temperature to 100-110°C within 80-90 minutes and keeping it for 240-250 minutes; then raising the temperature to 120-130°C within 30-40 minutes and keeping it for 120-130 minutes ;Finally, heat up to 170-180°C within 170-180min, and keep it for 150-160min; pressurization and curing steps are as follows: when the temperature rises to 100-110°C, pressurize 0.3-0.4MPa to close the mold; heat preservation ends at 100-110°C pressurize at 1.0-1.2MPa; when the temperature rises to 120-130°C, pressurize at 2.0-2.2MPa after deflation for 1-2min; -3.2MPa; when holding at 120-130°C for 120-130min, deflate for 1-2min, pressurize at 4.0-4.2MPa, keep the pressure until the end of the program, after the curing is over, let the overall molding tooling of the expansion section cool down to room temperature naturally, Demoulding and taking out the expanded section product.

Based on the same idea, the present invention also provides a light-weight, low-ablation nozzle expansion section.

The above-mentioned one or more technical solutions of the present invention have the following technical effects:

The embodiment of the present invention provides a light-weight, low-ablation nozzle expansion section and its preparation method. According to the functional requirements of different parts of the expansion section, the double-layer structure and size of the expansion section are reasonably designed to meet the different performance requirements of different parts. , to achieve the goal of light weight to increase the payload of the engine. Compared with the traditional carbon cloth/high silica cloth reinforced phenolic resin composite winding expansion section, and the improved carbon/silicon carbide composite winding expansion section based on the winding expansion section, the composite nozzle expansion section, through the partition function design , so that it has better anti-ablation performance in the main ablation area of the small end, and the other non-ablation areas have good overall structural stability and low density advantages. The overall prefabricated body of the expansion section is formed by carbon cloth + acupuncture, which greatly The interlaminar shear strength is improved, and the risk of structural delamination that is prone to occur in the design of the thin-walled structure of the winding expansion section after high-temperature carbonization is avoided.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that are required in the description of the embodiments or the prior art. Apparently, the drawings in the following description are only exemplary, and those skilled in the art can also obtain other implementation drawings according to the provided drawings without creative work.

Figure 1. A flow chart for the preparation of a lightweight, low-ablation nozzle expansion section;

Figure 2. The curing tooling diagram of the prefabricated part at the small end of the expansion section;

Figure 3. Schematic diagram of the prefabricated part at the small end of the expansion section;

Figure 4. The overall prefabricated body diagram of the composite expansion section;

Figure 5. Overall molding tooling diagram of composite expansion section;

Figure 6. Composite expansion section product diagram (blank);

Among them, 1. Male mold, 2. Collar, 3. Screw, 4. Female mold, 5. Block, 6. Top cover, 7. Female mold, 8. Male mold, 9. Screw, 10. Chassis.

Detailed ways

Example 1

As shown in Figure 1, a method for preparing a light-weight, low-ablation nozzle expansion section includes:

S1: Preparation of the small end of the expansion section: Mix the high-carbon residual phenolic resin, polyacrylonitrile-based chopped carbon fiber, and solvent in proportion to form a premix. After the premix is desolventized, put it into the curing tooling of the prefabricated part of the expansion section. After being heated and pressurized by the press, it is solidified into a prefabricated part blank, and the prefabricated part blank is machined to obtain a prefabricated part;

预混料脱溶剂处理合格后，称取适量的预混料，装入如图1所示的扩张段小端预制件固化工装内，完成扩张段小端预制件的装模。扩张段小端预制件固化工装包括垫块、阴模、阳模、套环。阴模与套环之间使用螺钉连接，其它工装之间通过配合连接。预混料装模前，先将阴模和垫块通过配合连接，阴模与套环通过螺钉连接，使垫块、阴模和套环三者之间形成一个腔体，称量好的预混料均匀铺放入腔体中，最后加盖阳模，即完成扩张段小端预制件的装模；将装模后的扩张段小端预制件固化工装放置于压机上，准备固化，压机加热固化步骤为：在50-60min内由室温升温至80-90℃，保持120-130min；然后在50-60min内升温至100-110℃，保持90-100min；最后在140-150min内升温至170-180℃，保持150-160min；压机加压固化步骤为：80-90℃时加压1.0-1.5MPa合模；100-110℃时加压3.0-3.5MPa；在100-110℃下保温60-70min时，放气1-2min，加压6.0-6.5MPa；100-110℃下保温90-100min时，放气1-2min后加压10.0-10.5MPa，保压一直到程序结束，固化结束后，待固化工装自然冷却至室温，脱模取出小端预制件毛坯；将预制件毛坯机加以获得图3所示的预制件制品。Specifically, industrial alcohol is used as the solvent, wherein the mass ratio of high carbon residue phenolic resin, polyacrylonitrile-based chopped carbon fiber and solvent is 1:1.4-1.6:2.8-3.2, wherein the mixing order is first according to the above ratio Mix high carbon residue phenolic resin and industrial alcohol evenly by mechanical stirring, then add polyacrylonitrile-based chopped carbon fiber, knead and squeeze repeatedly, so that the resin solution and carbon fiber are fully mixed to form a premix, premix The material is desolvated at 70-80°C. It can be desolvated in an oven, or it can be desolvated by other methods, and the volatile x content in the premix is kept at 3.0% ≤ x ≤ 5.5%. The volatile content of the premix test method : Take a certain amount (20-40g) of premix, weigh m1, put it in an oven at (103-107) °C, keep it warm for (29-31) min, take it out and let it cool to room temperature, and then weigh m2, then Volatile x is calculated as:

After the desolvation treatment of the premix is qualified, an appropriate amount of premix is weighed and put into the curing tooling of the small end preform of the expansion section as shown in Figure 1 to complete the molding of the small end preform of the expansion section. The curing tooling for the prefabricated part at the small end of the expansion section includes spacers, female molds, male molds, and collars. Screws are used to connect the female mold and the collar, and other toolings are connected by fit. Before loading the premix into the mould, the female mold and the spacer are first connected by fit, and the female mold and the collar are connected by screws, so that a cavity is formed between the spacer, the female mold and the collar, and the weighed premixed Put the mixed materials evenly into the cavity, and finally cover the positive mold, that is, complete the mold loading of the small end preform of the expansion section; place the curing tool of the small end preform of the expansion section after the mold loading on the press, ready for curing, and the press is heated and solidified The steps are: raise the temperature from room temperature to 80-90°C within 50-60min and keep it for 120-130min; then raise the temperature to 100-110°C within 50-60min and keep it for 90-100min; 180°C, keep for 150-160min; the pressing and curing steps of the press are: pressurize 1.0-1.5MPa at 80-90°C to close the mold; pressurize 3.0-3.5MPa at 100-110°C; At -70min, deflate for 1-2min and pressurize at 6.0-6.5MPa; when holding at 100-110°C for 90-100min, deflate for 1-2min and then pressurize at 10.0-10.5MPa, keep the pressure until the end of the program, and the curing is over Finally, the solidified tooling is naturally cooled to room temperature, and the small-end preform blank is removed from the mold; the preform blank machine is used to obtain the preform product shown in Figure 3.

S2: Preparation of the large end of the expansion section: on the outer side of the preform and the large end of the expansion section, the composite expansion section prefabricated body is braided using carbon cloth/mesh tire + needle punching molding technology. After it is made, it is impregnated with phenolic resin. In the molding tooling, it is heated and pressurized by the press to be solidified into a composite expansion section product. The expansion section blank is partially machined in the subsequent nozzle production and assembled with the nozzle casing in place;

Specifically, the carbon cloth is T800 polyacrylonitrile-based carbon fiber twill cloth, and the mesh tire is T700 polyacrylonitrile-based carbon fiber, wherein the carbon cloth and the carbon fiber mesh tire are alternately laminated, and the laying direction is parallel to the direction of the busbar of the expansion section. The overall prefabricated body of the composite expansion section is fixed and formed into a conical structure by the stabbing process; after the preform of the composite expansion section is molded, the preform is dehumidified under the condition of 105-110°C/2h; after dehumidification, the preform is packed in a vacuum bag Cover to form a closed space, reserve a vacuum port at the small end, and reserve several glue inlets at the large end. Check the vacuum degree of the vacuum bag before impregnation, and it is required that the vacuum degree can be continuously maintained ≤ -0.07MPa. Weigh a certain amount of phenolic resin, put it in a clean container, and then connect the phenolic resin in the container with the preform glue inlet through the PE injection tube. When the vacuum degree meets the requirements, open the preform glue inlet valve, and the phenolic resin starts to flow Under vacuum suction, it is slowly sucked into the preform until the preform is completely saturated with phenolic resin, and the resin impregnation process of the preform is completed. The prefabricated body impregnated with resin is put into the overall molding tooling of the composite expansion section, and is cured by heating and pressing. The integral molding tooling is shown in Fig. 5, is made up of female die, male die, chassis, top cover, screw. First connect the male mold and the chassis with screws, then install the impregnated prefabricated body on the male mold, then close the female mold and the top cover in turn, and the molding is completed; the molded tooling is placed on the press, ready to be cured ;The heating and curing steps of the press are: within 80-90min, the temperature is raised from room temperature to 100-110°C, and kept for 240-250min; Internally raise the temperature to 170-180°C and keep it for 150-160min; the pressing and curing steps of the press are: pressurize 0.3-0.4MPa to close the mold when the temperature is raised to 100-110°C; pressurize 1.0- 1.2MPa; when the temperature rises to 120-130°C, deflate for 1-2min and then pressurize 2.0-2.2MPa; when holding at 120-130°C for 60-70min, deflate for 1-2min, pressurize 3.0-3.2MPa; 120- When holding at 130°C for 120-130 minutes, deflate for 1-2 minutes, pressurize at 4.0-4.2 MPa, and keep the pressure until the end of the program. After curing, the overall molded tooling of the expansion section is naturally cooled to room temperature, and the product of the expansion section is removed from the mold. ,As shown in Figure 6.

Polyacrylonitrile-based carbon fiber/high carbon residual phenolic resin material oxyacetylene wire ablation rate (executive standard GJB 323B) is 0.02-0.03mm/s, which is 50% lower than the ablation rate (0.05-0.06) of traditional winding expansion section materials , in addition, compared with the winding expansion section, the carbon fiber/phenolic material has a simpler preparation process and greatly improved quality controllability.

Claims (8)

1. A method for preparing light-weight, low-ablation nozzle expansion section, characterized in that, comprising: S1: Preparation of the small end of the expansion section: Mix the high-carbon residual phenolic resin, polyacrylonitrile-based chopped carbon fiber, and solvent in proportion to form a premix. After the premix is desolventized, put it into the curing tooling of the prefabricated part of the expansion section. After being heated and pressurized by the press, it is solidified into a prefabricated part blank, and the prefabricated part blank is machined to obtain a prefabricated part; S2: Preparation of the large end of the expansion section: on the outer side of the preform and the large end of the expansion section, the composite expansion section prefabricated body is braided using carbon cloth/mesh tire + needle punching molding technology. After it is made, it is impregnated with phenolic resin. In the molding tooling, it is heated and pressurized by the press to be solidified into a composite expansion section product. The expansion section blank is partially machined in the subsequent nozzle production and assembled with the nozzle casing in place. 2. the preparation method of light weight according to claim 1, low ablation nozzle expansion section, it is characterized in that: solvent adopts industrial alcohol in described S1, wherein, high carbon residual phenolic resin, polyacrylonitrile base chopped carbon fiber The mass ratio to the solvent is 1:1.4-1.6:2.8-3.2. 3. The method according to claim 1, characterized in that: the premix in S1 is desolvated at 70-80°C to keep the volatile x content in the premix 3.0%≤x≤5.5%. 4. The preparation method of light-weight, low-ablation nozzle expansion section according to claim 1, characterized in that: the heating and curing step of the S1 medium press is: heating from room temperature to 80-90°C within 50-60min , keep for 120-130min; then raise the temperature to 100-110°C within 50-60min, keep for 90-100min; finally raise the temperature to 170-180°C within 140-150min, keep for 150-160min; press press curing steps are: Pressurize 1.0-1.5MPa at 80-90°C to close the mold; pressurize at 100-110°C to 3.0-3.5MPa; hold at 100-110°C for 60-70min, deflate for 1-2min, pressurize at 6.0-6.5MPa ;When holding at 100-110°C for 90-100min, pressurize 10.0-10.5MPa after deflation for 1-2min, keep the pressure until the end of the program. Pieces of rough. 5. The preparation method of light weight and low-ablation nozzle expansion section according to claim 1, characterized in that: the carbon cloth in the S2 is T800 polyacrylonitrile-based carbon fiber twill cloth, and the mesh tire is T700 polyacrylonitrile Base carbon fiber, in which carbon cloth and carbon fiber mesh tires are alternately laminated, and the laying direction is parallel to the direction of the busbar of the expansion section, and is fixed and formed into a composite expansion section integral prefabricated body with a tapered structure through a needle punching process. 6. The method for preparing the light-weight, low-ablation nozzle expansion section according to claim 1, characterized in that: after the prefabricated body of the composite expansion section in S2 is compression molded, the prefabricated Body dehumidification treatment. 7. The method for preparing the expansion section of the light-weight and low-ablation nozzle according to claim 1, characterized in that: the heating and curing step of the S2 medium press is: heating from room temperature to 100-110°C within 80-90min , keep for 240-250min; then raise the temperature to 120-130°C within 30-40min, keep for 120-130min; finally raise the temperature to 170-180°C within 170-180min, keep for 150-160min; press press curing steps are: When the temperature rises to 100-110°C, pressurize 0.3-0.4MPa to close the mold; when the heat preservation ends at 100-110°C, pressurize 1.0-1.2MPa; 2.2MPa; when holding at 120-130°C for 60-70min, deflate for 1-2min, pressurize at 3.0-3.2MPa; when holding at 120-130°C for 120-130min, deflate for 1-2min, pressurize at 4.0-4.2MPa , keep the pressure until the end of the program. After the curing is completed, the overall molding tooling of the expansion section is naturally cooled to room temperature, and the product of the expansion section is removed from the mold. 8. A light-weight, low-ablation nozzle expansion section, characterized in that: the light-weight, low-ablation expansion section is prepared by any one of the methods of claims 1-7.

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