An anti-erosion material, its preparation method and application

Abstract

The application discloses an anti-erosion material and a preparation method and application thereof, and belongs to the technical field of inner heat-insulating layer materials of solid rocket engine combustion chambers. The preparation raw materials of the anti-erosion material include aramid fiber fabric, modified EPDM matrix material and phenolic resin, the modified EPDM matrix material is prepared from EPDM, modified EPDM, white carbon black, zinc borate, dicumyl peroxide and triallyl isocyanurate through a rubber mixing process. The anti-erosion material in the application has lower density and lower thermal conductivity on the basis of maintaining the ablation performance of traditional materials, and can reduce the negative mass of the aircraft. The inner heat-insulating layer is prepared by using a one-time curing method, so that the production efficiency is greatly improved; meanwhile, the interface cleaning and the brushing of the adhesive, which must be carried out for bonding different materials, are omitted, the hidden troubles of air inclusions and bulges are eliminated, and the probability of interface debonding is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal insulation layer materials in a solid rocket engine combustion chamber, and particularly relates to an anti-scour material and a preparation method and application thereof. Background Art

[0002] With the increasing demands for aircraft range and delivery capabilities, as well as increases in propellant charge and engine combustion duration, the requirements for the ablation and scour resistance of solid rocket motor combustion chamber insulation are becoming increasingly stringent. Traditional single rubber-based insulation layers are no longer sufficient. In recent years, carbon fiber / phenolic-nitrile composite materials have been developed and used in conjunction with other rubber insulation materials as an anti-scour layer in areas of the insulation layer where scour is most severe, achieving excellent results.

[0003] However, during ground-based ignition tests of solid rocket engines, the propellant releases a significant amount of heat. Due to the high thermal conductivity of carbon fiber, this heat is easily transferred to the bonding interface and even the engine casing, leading to test failure. Furthermore, the relatively high density of carbon fiber increases the negative mass of the solid rocket engine, affecting the effective range of the aircraft.

[0004] Furthermore, with the rapid adoption of EPDM insulation materials, which offer excellent overall performance in terms of low density and ablation resistance, an increasing number of EPDM insulation materials, carbon fiber / phenolic-nitrile erosion-resistant materials, and EPDM insulation sandwich structures are being used in areas of solid rocket engines prone to severe ablation. However, the polarity of the NBR and EPDM rubber in the carbon fiber / phenolic-nitrile erosion-resistant materials differ significantly, leading to weak bonding between EPDM and both carbon fiber and nitrile. This often leads to defects such as air entrapment and bulging during use, which can lead to the failure of the insulation layer in severe cases.

[0005] Furthermore, the current bonding method for carbon fiber / phenolic-nitrile composite materials and rubber insulation materials mainly adopts a secondary curing process, and the layers need to be brushed with glue. The bonding process is complicated, the production cycle is long, and there are many quality risks, which leads to an increase in product failure rate. Summary of the Invention

[0006] In response to the above-mentioned existing technologies, the present invention uses aramid fiber with lower thermal conductivity and density than carbon fiber to design a scouring material with low density, low thermal conductivity and good compatibility with EPDM insulation material. At the same time, a bonding method for the material is provided to solve the bonding problem of the EPDM insulation material and the fiber / phenolic-EPDM anti-scouring material sandwich structure, simplify the bonding process, reduce quality risks, and improve the reliability of the structure.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is to provide an anti-scour material, the raw materials for preparing the material include the following components in parts by weight:

[0008] 45-55 parts of aramid fiber fabric, 20-35 parts of modified EPDM rubber matrix material and 10-35 parts of phenolic resin;

[0009] The modified EPDM rubber matrix material is prepared through a rubber refining process using EPDM rubber, modified EPDM rubber, white carbon black, zinc borate, dicumyl peroxide and triallyl isocyanurate as raw materials; the mass ratio of EPDM rubber, modified EPDM rubber, white carbon black, zinc borate, dicumyl peroxide and triallyl isocyanurate is 60:40:10-2:8-10:1-4:2-5; the modified EPDM rubber includes sulfonated EPDM rubber and acrylonitrile-grafted EPDM rubber.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, the raw materials for preparing the anti-scour material include the following components in parts by mass:

[0012] 54 parts of aramid fiber fabric, 23 parts of modified EPDM rubber matrix material and 23 parts of phenolic resin.

[0013] Furthermore, the aramid fiber fabric is an aramid fiber weft-knitted fabric with a thickness of 1 to 4 mm.

[0014] Furthermore, the phenolic resin is at least one of a thermosetting phenolic resin, a thermoplastic phenolic resin and a modified phenolic resin.

[0015] Furthermore, the phenolic resin is a barium phenolic resin.

[0016] Further, the modified EPDM rubber matrix material is prepared by the following steps:

[0017] Add modified EPDM rubber, white carbon black, zinc borate, dicumyl peroxide and triallyl isocyanurate to EPDM rubber in sequence. Each time a raw material is added, thinly pass it 4 times. After all the raw materials are added, thinly pass it 12 times to obtain the product.

[0018] Furthermore, the mass ratio of the sulfonated EPDM rubber to the acrylonitrile-grafted EPDM rubber is 1:1-3.

[0019] Further, sulfonated EPDM rubber is prepared by the following steps:

[0020] Dissolve EPDM rubber in n-heptane, then add concentrated sulfuric acid and acetic anhydride to the resulting solution, react at room temperature for 30 minutes, and then add ethanol to terminate the reaction; then add an ethanol solution of metal acetate, stir, flash evaporate to remove the solvent, and dry the residue at 100°C to obtain;

[0021] Acrylonitrile grafted EPDM rubber is prepared by the following steps:

[0022] The EPDM is dissolved in n-heptane, then a xylene solution of azobisisobutyronitrile and a xylene solution of acrylonitrile are added in an inert gas atmosphere; after the reaction is completed, the product is precipitated with acetone, the obtained precipitate is subjected to Soxhlet extraction with N,N'-dimethylformamide, and then dried at 60 DEG C under vacuum.

[0023] The application further discloses a preparation method of the anti-erosion material.

[0024] S1: dissolving a modified EPDM matrix material in a mixed solvent, then adding a phenolic resin into the obtained solution, stirring until the phenolic resin is completely dissolved, and obtaining a glue solution; the mixed solvent is prepared by mixing n-heptane and ethyl acetate at a volume ratio of 2.5-5:2.5-4; the glue solution is prepared by mixing the modified EPDM matrix material, the phenolic resin and the mixed solvent at a material solution ratio of 0.5g:0.5g:4-6mL;

[0025] S2: uniformly distributing the glue solution in aramid fiber fabric by vacuum impregnation to obtain an impregnated fabric;

[0026] S3: evaporating the mixed solvent in the impregnated fabric by ventilation drying, air blowing or heating treatment, and obtaining the anti-erosion material; the ventilation drying is performed for 6-10h, the air blowing is performed for 2-3h, and the heating is performed at a temperature of 40-60 DEG C.

[0027] The application further discloses application of the anti-erosion material as a heat-insulating layer in a solid rocket engine combustion chamber, and a preparation method of the heat-insulating layer in the solid rocket engine combustion chamber.

[0028] (1) according to the structure size requirement of the engine heat-insulating layer, cutting the EPDM sheet and the anti-erosion material into corresponding sizes and shapes; the cut EPDM sheet comprises a bottom layer EPDM sheet and a surface layer EPDM sheet;

[0029] (2) performing sand blasting, cleaning and glue sealing treatment on the inner surface of the engine shell, and then performing air extraction and standing for 2h;

[0030] (3) wrapping the bottom layer EPDM sheet with an air bag and sending the bottom layer EPDM sheet into the inner cavity of the shell, and hot pressing the bottom layer EPDM sheet with the air bag; the hot pressing temperature is 80 DEG C, the hot pressing pressure is 1.0MPa, and the hot pressing time is 1h;

[0031] (4) laying the cut anti-erosion material on the surface of the bottom layer EPDM sheet, and hot pressing the anti-erosion material with an air bag; the hot pressing temperature is 80 DEG C, the hot pressing pressure is 1.0MPa, and the hot pressing time is 1.5h;

[0032] (5) laying the surface layer EPDM sheet on the surface of the anti-erosion material, and cold pressing the surface layer EPDM sheet and the anti-erosion material with an air bag; the cold pressing pressure is 0.7MPa, and the cold pressing time is 2h;

[0033] (6) Airbag pressure curing is used, the curing temperature is 160°C, the curing pressure is 1.0 MPa, and the curing time is 2 h;

[0034] (7) Cool to room temperature.

[0035] The beneficial effects of the present invention are:

[0036] (1) The anti-scour material of the present invention has a lower density (less than 1.25g / cm2) while maintaining the ablation performance of traditional materials. 3 ) and lower thermal conductivity (less than 0.04W / (K·m)), which can reduce the passive mass of the aircraft.

[0037] (2) The anti-scour material of the present invention contains sulfonated EPDM rubber and acrylonitrile-grafted EPDM rubber. The sulfonated EPDM rubber can enhance the bonding performance between the modified EPDM rubber matrix and aramid fabric, improving quality reliability. The acrylonitrile-grafted EPDM rubber can enhance the bonding strength between the anti-scour material and other thermal insulation materials such as nitrile butadiene rubber. The combined use of the two modified EPDM rubbers can significantly improve the reliability of the thermal insulation structure.

[0038] (3) The anti-scour material of the present invention also contains white carbon black, zinc borate, diisopropylbenzene peroxide and triallyl isocyanurate; among them, white carbon black can enhance the strength and wear resistance of the material, and zinc borate helps to improve the flame retardancy and thermal stability of the material; diisopropylbenzene peroxide (DCP) and triallyl isocyanurate (TAIC) are used as cross-linking agents to further enhance the cross-linking density and heat resistance of the material, so that the modified EPDM rubber matrix material has higher strength and longer service life while maintaining good elasticity.

[0039] (4) The bonding method adopted by the present invention in preparing the thermal insulation layer in the combustion chamber of a solid rocket engine is changed from the traditional secondary curing to a single curing, thereby avoiding the bonding of raw and cooked interfaces, simplifying the production process, and greatly improving production efficiency; at the same time, it eliminates the need for cleaning the interface and applying the adhesive required for bonding different materials, eliminates the hidden dangers of air entrapment and bulging at the interface, and greatly reduces the probability of interface debonding. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The thermal insulation layer is prepared by the process in Comparative Example 1;

[0041] Figure 2 The thermal insulation layer is prepared using the process in Example 1. DETAILED DESCRIPTION

[0042] The EPDM rubber used in the embodiment of the present invention is Jilin Chemical 4045.

[0043] The sulfonated EPDM rubber used is prepared by the following steps:

[0044] EPDM is dissolved in n-heptane to obtain a rubber solution with a concentration of 60 mg / 100 mL; concentrated sulfuric acid and acetic anhydride with twice the molar number of double bonds in the raw rubber are added to the rubber solution at room temperature, and the mixture is reacted at room temperature for 30 minutes. The sulfonation reaction is terminated with ethanol, and the sulfonated EPDM is treated with an excess of 40 wt% zinc acetate ethanol solution, stirred, and the solvent is flash-evaporated with boiling water. The precipitate is dried at 100° C. to obtain the sulfonated EPDM.

[0045] The acrylonitrile grafted EPDM rubber used is prepared by the following steps:

[0046] Add the measured amount of EPDM and n-heptane into a four-necked flask protected by nitrogen and stir at 60°C. After the EPDM is completely dissolved (the concentration of EPDM is 60 mg / 100 mL), add xylene (2.5 g / 100 mL) dissolved with azobisisobutyronitrile, and then add a xylene solution (30 g / 100 mL) of acrylonitrile dropwise within 10 minutes. After the reaction is complete, precipitate the reaction product with acetone while hot. After all the precipitates are Soxhlet extracted with N,N'-dimethylformamide, vacuum dry at 60°C to obtain the acrylonitrile-grafted EPDM product.

[0047] The remaining raw materials are commercially available.

[0048] The specific implementation methods of the present invention are described in detail below with reference to the embodiments.

[0049] Example 1

[0050] An anti-scour material, the raw materials for its preparation include the following components in parts by mass:

[0051] 52 parts of aramid fiber fabric, 24 parts of modified EPDM rubber matrix material, and 24 parts of barium phenolic resin; wherein the aramid fiber fabric is a 2 mm thick aramid fiber double-sided weft-knitted fabric; the modified EPDM rubber matrix material is prepared using the following raw materials in parts by mass:

[0052] 60 parts of EPDM rubber, 20 parts of sulfonated EPDM rubber, 20 parts of acrylonitrile-grafted EPDM rubber, 10 parts of white carbon black, 8 parts of zinc borate, 3 parts of dicumyl peroxide (DCP), and 2 parts of triallyl isocyanurate (TAIC); the preparation method is to add the EPDM rubber into an open mixing mill, and then add the sulfonated EPDM rubber, acrylonitrile-grafted EPDM rubber, white carbon black, zinc borate, dicumyl peroxide and triallyl isocyanurate in sequence, each time adding a raw material, thinly pass through 4 times, and after all the raw materials are added, thinly pass through 12 times to obtain the product.

[0053] The anti-scour material in this embodiment is prepared by the following steps:

[0054] S1: dissolving the modified EPDM matrix material in a mixed solvent, then adding the barium phenolic resin to the resulting solution and stirring until completely dissolved to obtain a glue solution; wherein the mixed solvent is formed by mixing n-heptane and ethyl acetate in a volume ratio of 1:1; the material-liquid ratio of the modified EPDM matrix material and the barium phenolic resin to the mixed solvent is 0.5 g:0.5 g:5 mL;

[0055] S2: Vacuum dipping is used to evenly distribute the adhesive solution in the aramid fiber fabric to obtain a dipped fabric. The specific process of vacuum dipping is as follows:

[0056] Place polytetrafluoroethylene debonding paper, aramid fiber fabric, guide net, and release cloth layer by layer on the dipping platform, reserve the resin dipping tube and vacuum interface, then package the vacuum bag film, close the dipping tube valve, connect the vacuum pump and evacuate to a pressure of ≤-0.09MPa, check the overall vacuum degree, maintain the vacuum for 15 minutes, start to put the dipping tube into the glue solution, open the hose valve and start vacuum dipping, continue to vacuum so that the impregnation liquid fully penetrates the aramid fiber fabric, stop vacuuming when the resin glue reaches the glue outlet, slowly return to normal pressure, soak for 5 minutes, and ensure that the impregnation liquid is completely soaked;

[0057] S3: Place the impregnated fabric in a ventilated and dry place for 8 hours to allow the mixed solvent in the impregnated fabric to evaporate.

[0058] The anti-scour material of this embodiment is used to prepare the thermal insulation layer in the combustion chamber of a solid rocket engine, which specifically includes the following steps:

[0059] (1) According to the structural size requirements of the engine insulation layer, the EPDM sheet and the anti-scour material are cut into corresponding sizes and shapes. The cut EPDM sheet includes a bottom EPDM sheet and a surface EPDM sheet;

[0060] (2) Sandblast, clean, and seal the inner surface of the engine housing, then ventilate and air dry for 2 hours;

[0061] (3) Wrap the bottom EPDM sheet with an airbag and send it into the inner cavity of the shell, and hot press it with the airbag. The hot pressing temperature is 80°C, the hot pressing pressure is 1.0 MPa, and the hot pressing time is 1 hour;

[0062] (4) Lay the cut anti-scour material on the surface of the bottom EPDM sheet and hot press it with an air bag. The hot pressing temperature is 80°C, the hot pressing pressure is 1.0 MPa, and the hot pressing time is 1.5 hours;

[0063] (5) The surface of the anti-scouring material is coated with a layer of EPDM sheet, and the EPDM sheet is cold-pressed and attached to the surface of the anti-scouring material by air bag pressurization, with a cold-pressing pressure of 0.7 MPa and a cold-pressing time of 2 h;

[0064] (6) The EPDM sheet is cured by air bag pressurization, with a curing temperature of 160℃, a curing pressure of 1.0 MPa, and a curing time of 2 h;

[0065] (7) The engine shell is removed after the engine shell is cooled to room temperature in the furnace, and the bonding of the inner thermal insulation layer of the engine is completed.

[0066] Example 2

[0067] An anti-scouring material is prepared from the following components by mass:

[0068] The anti-scouring material is prepared from the following components by mass:

[0069] The anti-scouring material is prepared from the following components by mass:

[0070] The anti-scouring material is prepared from the following components by mass:

[0071] S1: The modified EPDM matrix material is dissolved in a mixed solvent, and then the barium phenolic resin is added to the obtained solution, and stirred until completely dissolved to obtain a glue solution; wherein the mixed solvent is prepared by mixing n-heptane and ethyl acetate in a volume ratio of 1:1; the material-to-liquid ratio of the modified EPDM matrix material and the barium phenolic resin to the mixed solvent is 0.5 g:0.5 g:5 mL;

[0072] S2: The glue solution is uniformly distributed in the aramid fiber fabric by vacuum impregnation to obtain an impregnated fabric; the specific process of vacuum impregnation is as follows:

[0073] Place polytetrafluoroethylene debonding paper, aramid fiber fabric, guide net, and release cloth layer by layer on the dipping platform, reserve the resin dipping tube and vacuum interface, then package the vacuum bag film, close the dipping tube valve, connect the vacuum pump and evacuate to a pressure of ≤-0.09MPa, check the overall vacuum degree, maintain the vacuum for 15 minutes, start to put the dipping tube into the glue solution, open the hose valve and start vacuum dipping, continue to vacuum so that the impregnation liquid fully penetrates the aramid fiber fabric, stop vacuuming when the resin glue reaches the glue outlet, slowly return to normal pressure, soak for 5 minutes, and ensure that the impregnation liquid is completely soaked;

[0074] S3: drying the impregnated fabric at a temperature of 50° C. to volatilize the mixed solvent in the impregnated fabric.

[0075] The anti-scour material of this embodiment is used to prepare the thermal insulation layer in the combustion chamber of a solid rocket engine, which specifically includes the following steps:

[0076] (1) According to the structural size requirements of the engine insulation layer, the EPDM sheet and the anti-scour material are cut into corresponding sizes and shapes. The cut EPDM sheet includes a bottom EPDM sheet and a surface EPDM sheet;

[0077] (2) Sandblast, clean, and seal the inner surface of the engine housing, then ventilate and air dry for 2 hours;

[0078] (3) Wrap the bottom EPDM sheet with an airbag and send it into the inner cavity of the shell, and hot press it with the airbag. The hot pressing temperature is 80°C, the hot pressing pressure is 1.0 MPa, and the hot pressing time is 1 hour;

[0079] (4) Lay the cut anti-scour material on the surface of the bottom EPDM sheet and hot press it with an air bag. The hot pressing temperature is 80°C, the hot pressing pressure is 1.0 MPa, and the hot pressing time is 1.5 hours;

[0080] (5) Lay the surface EPDM sheet on the surface of the anti-scour material, and press it with the airbag under cold pressure. The cold pressing pressure is 0.7 MPa and the cold pressing time is 2 h.

[0081] (6) Airbag pressure curing is used, the curing temperature is 160°C, the curing pressure is 1.0 MPa, and the curing time is 2 h;

[0082] (7) After cooling to room temperature in the furnace, remove the engine housing and complete the bonding of the heat insulation layer inside the engine.

[0083] Example 3

[0084] An anti-scour material, the raw materials for its preparation include the following components in parts by mass:

[0085] 54 parts of aramid fiber fabric, 23 parts of modified EPDM rubber matrix material and 23 parts of barium phenolic resin; wherein the aramid fiber fabric is a 2 mm thick aramid fiber double-sided weft knitted fabric; the modified EPDM rubber matrix material is prepared using the following raw materials in parts by mass:

[0086] 60 parts of EPDM rubber, 20 parts of sulfonated EPDM rubber, 20 parts of acrylonitrile-grafted EPDM rubber, 10 parts of white carbon black, 8 parts of zinc borate, 3 parts of dicumyl peroxide (DCP), and 2 parts of triallyl isocyanurate (TAIC); the preparation method is to add the EPDM rubber into an open mixing mill, and then add the sulfonated EPDM rubber, acrylonitrile-grafted EPDM rubber, white carbon black, zinc borate, dicumyl peroxide and triallyl isocyanurate in sequence, each time adding a raw material, thinly pass through 4 times, and after all the raw materials are added, thinly pass through 12 times to obtain the product.

[0087] The anti-scour material in this embodiment is prepared by the following steps:

[0088] S1: dissolving the modified EPDM matrix material in a mixed solvent, then adding the barium phenolic resin to the resulting solution and stirring until completely dissolved to obtain a glue solution; wherein the mixed solvent is formed by mixing n-heptane and ethyl acetate in a volume ratio of 1:1; the material-liquid ratio of the modified EPDM matrix material and the barium phenolic resin to the mixed solvent is 0.5 g:0.5 g:5 mL;

[0089] S2: Vacuum dipping is used to evenly distribute the adhesive solution in the aramid fiber fabric to obtain a dipped fabric. The specific process of vacuum dipping is as follows:

[0090] Place polytetrafluoroethylene debonding paper, aramid fiber fabric, guide net, and release cloth layer by layer on the dipping platform, reserve the resin dipping tube and vacuum interface, then package the vacuum bag film, close the dipping tube valve, connect the vacuum pump and evacuate to a pressure of ≤-0.09MPa, check the overall vacuum degree, maintain the vacuum for 15 minutes, start to put the dipping tube into the glue solution, open the hose valve and start vacuum dipping, continue to vacuum so that the impregnation liquid fully penetrates the aramid fiber fabric, stop vacuuming when the resin glue reaches the glue outlet, slowly return to normal pressure, soak for 5 minutes, and ensure that the impregnation liquid is completely soaked;

[0091] S3: Place the impregnated fabric in a ventilated and dry place for 8 hours to allow the mixed solvent in the impregnated fabric to evaporate.

[0092] The anti-scour material of this embodiment is used to prepare the thermal insulation layer in the combustion chamber of a solid rocket engine, which specifically includes the following steps:

[0093] (1) According to the structural size requirements of the engine insulation layer, the EPDM sheet and the anti-scour material are cut into corresponding sizes and shapes. The cut EPDM sheet includes a bottom EPDM sheet and a surface EPDM sheet;

[0094] (2) Sandblast, clean, and seal the inner surface of the engine housing, then ventilate and air dry for 2 hours;

[0095] (3) Wrap the bottom EPDM sheet with an airbag and send it into the inner cavity of the shell, and hot press it with the airbag. The hot pressing temperature is 80°C, the hot pressing pressure is 1.0 MPa, and the hot pressing time is 1 hour;

[0096] (4) Lay the cut anti-scour material on the surface of the bottom EPDM sheet and hot press it with an air bag. The hot pressing temperature is 80°C, the hot pressing pressure is 1.0 MPa, and the hot pressing time is 1.5 hours;

[0097] (5) Lay the surface EPDM sheet on the surface of the anti-scour material, and press it with the airbag under cold pressure. The cold pressing pressure is 0.7 MPa and the cold pressing time is 2 h.

[0098] (6) Airbag pressure curing is used, the curing temperature is 160°C, the curing pressure is 1.0 MPa, and the curing time is 2 h;

[0099] (7) After cooling to room temperature in the furnace, remove the engine housing and complete the bonding of the heat insulation layer inside the engine.

[0100] Comparative Example 1

[0101] An anti-scour material, the composition and preparation method are the same as those in Example 1.

[0102] The anti-scour material in this comparative example is used to prepare the thermal insulation layer in the combustion chamber of a solid rocket engine, which specifically includes the following steps:

[0103] (1) According to the structural size requirements of the engine insulation layer, the EPDM sheet and the anti-scour material are cut into corresponding sizes and shapes. The cut EPDM sheet includes a bottom EPDM sheet and a surface EPDM sheet;

[0104] (2) Sandblast, clean, and seal the inner surface of the engine housing, then ventilate and air dry for 2 hours;

[0105] (3) Wrap the bottom EPDM sheet with an airbag and send it into the inner cavity of the shell, and hot press it with the airbag. The hot pressing temperature is 80°C, the hot pressing pressure is 1.0 MPa, and the hot pressing time is 1 hour;

[0106] (4) Lay the cut anti-scour material on the surface of the bottom EPDM sheet and hot press it with an air bag. The hot pressing temperature is 80℃, the hot pressing pressure is 1.0MPa, and the hot pressing time is 1.5h. Then perform the first curing at a curing temperature of 160℃, a curing time of 2h, and a pressure of 1.0MPa. After cooling to room temperature, remove the engine from the heating device.

[0107] (5) Clean the solidified flushing material with chemically pure ethyl acetate, let it air-dry for 1 hour, then apply CH238, and let it air-dry for another 1 hour;

[0108] (6) Lay the surface EPDM sheet on the surface of the anti-scour material, and press it with the airbag under hot pressing. The hot pressing pressure is 0.7 MPa and the hot pressing time is 2 hours.

[0109] (7) After hot pressing, check that there is no abnormality on the surface and then use air bag to pressurize for secondary curing. The curing temperature is 160℃, the curing pressure is 1.0MPa, and the curing time is 2h.

[0110] (8) After cooling to room temperature in the furnace, remove the engine housing and complete the bonding of the insulation layer inside the engine.

[0111] The difference between Comparative Example 1 and Example 1 is that, for the same anti-scour material, Example 1 adopts the one-time curing bonding of the present invention, while Comparative Example 1 adopts the traditional two-time curing bonding.

[0112] Comparative Example 2

[0113] An anti-scour material, the raw materials for its preparation include the following components in parts by mass:

[0114] 52 parts of carbon fiber fabric, 24 parts of nitrile rubber and 24 parts of barium phenolic resin; wherein the carbon fiber fabric is a 2mm thick carbon fiber weft knitted fabric preform.

[0115] The anti-scour material in this comparative example is prepared by the following steps:

[0116] S1: First, completely dissolve the nitrile rubber with ethyl acetate, then add the barium phenolic resin and stir evenly to form a glue solution;

[0117] S2: vacuum impregnation is used to evenly distribute the adhesive in the carbon fiber weft-knitted fabric preform, and the vacuum impregnation process is the same as that in Example 1;

[0118] S3: Place the impregnated fabric in a ventilated and dry place for 8 hours to allow the solvent in the impregnated fabric to evaporate.

[0119] The anti-scour material in this comparative example is used to prepare the thermal insulation layer in the combustion chamber of a solid rocket engine, and the specific preparation process is the same as that in Example 1.

[0120] Experimental example

[0121] The materials and products obtained from the examples and the comparative examples were detected by the methods described in "Method for Determining Density of Composite Solid Propellant and Lining, Heat Insulating Material" (QJ917A-97), "Method for Determining Thermal Conductivity of Rubber by Hot-wire Method" (GB / T 11205-2009), "Method for Ablation Test of Ablation Material" (GJB323A-96) and the method for visually detecting the apparent quality of the heat insulating layer, and the results are shown in Table 1.

[0122] Table 1 Comparison of material performance data

[0123]

[0124] It can be seen from the results in Table 1 that the anti-scouring materials obtained from Examples 1 to 3 have lower density and lower thermal conductivity than the anti-scouring material obtained from Comparative Example 2, but the oxyacetylene linear ablation rate is basically the same. In addition, compared with Comparative Example 1, the present application can be directly bonded with the heat insulating layer without interface treatment, cleaning, gluing, secondary bonding, which not only reduces the process and production cycle, improves the production efficiency, but more importantly, saves the use of solvents, adhesives and other materials, reduces the cost, and reduces the possibility of defects such as bulging and debonding, greatly improves the product qualification rate. Moreover, the heat insulating layer prepared by the traditional secondary curing bonding preparation process in Comparative Example 1 is prone to bulging Figure 1 , while the heat insulating layer prepared by the one-time curing bonding process in the present application will not have bulging Figure 2 .

[0125] Although the specific embodiments of the present application are described in detail in combination with the examples, it should not be understood as limiting the protection scope of the present patent. Various modifications and variations made by those skilled in the art within the scope described in the claims are still within the protection scope of the present patent.

Claims

1. Application of erosion-resistant material as thermal insulation layer in combustion chamber of solid rocket motor, characterized in that: The method for preparing the thermal insulation layer in the combustion chamber of a solid rocket motor comprises the following steps: (1) According to the structural size requirements of the engine insulation layer, the EPDM sheet and the anti-scour material are cut into corresponding sizes and shapes. The cut EPDM sheet includes a bottom EPDM sheet and a surface EPDM sheet. The raw materials for preparing the anti-scour material include the following components in parts by weight: 45-55 parts of aramid fiber fabric, 20-35 parts of modified EPDM rubber matrix material and 10-35 parts of phenolic resin; The modified EPDM rubber matrix material is prepared by a rubber refining process using EPDM rubber, modified EPDM rubber, white carbon black, zinc borate, dicumyl peroxide, and triallyl isocyanurate as raw materials; the mass ratio of the EPDM rubber, modified EPDM rubber, white carbon black, zinc borate, dicumyl peroxide, and triallyl isocyanurate is 60:40:10-2:8-10:1-4:2-5; the modified EPDM rubber includes sulfonated EPDM rubber and acrylonitrile-grafted EPDM rubber; (2) Sandblast, clean, and seal the inner surface of the engine housing, then ventilate and air dry for 2 hours; (3) Wrap the bottom EPDM sheet with an airbag and send it into the inner cavity of the shell, and hot press it with the airbag. The hot pressing temperature is 80°C, the hot pressing pressure is 1.0 MPa, and the hot pressing time is 1 hour; (4) Lay the cut anti-scour material on the surface of the bottom EPDM sheet and hot press it with an air bag. The hot pressing temperature is 80°C, the hot pressing pressure is 1.0 MPa, and the hot pressing time is 1.5 hours; (5) Lay the surface EPDM sheet on the surface of the anti-scour material, and press it with the airbag under cold pressure. The cold pressing pressure is 0.7 MPa and the cold pressing time is 2 h. (6) Airbag pressure curing is used, the curing temperature is 160°C, the curing pressure is 1.0 MPa, and the curing time is 2 h; (7) Cool to room temperature.

2. The use according to claim 1, characterized in that The raw materials for preparing the anti-scour material include the following components in parts by mass: 54 parts of aramid fiber fabric, 23 parts of modified EPDM rubber matrix material and 23 parts of phenolic resin.

3. The use according to claim 1, characterized in that: The aramid fiber fabric is an aramid fiber weft-knitted fabric with a thickness of 1 to 4 mm.

4. The use according to claim 1 or 2, characterized in that: The phenolic resin is at least one of a thermosetting phenolic resin, a thermoplastic phenolic resin and a modified phenolic resin.

5. The use according to claim 4, characterized in that: The phenolic resin is barium phenolic resin.

6. The use according to claim 1, characterized in that The modified EPDM rubber matrix material is prepared by the following steps: Add modified EPDM rubber, white carbon black, zinc borate, dicumyl peroxide and triallyl isocyanurate to EPDM rubber in sequence. Each time a raw material is added, thinly pass it 4 times. After all the raw materials are added, thinly pass it 12 times to obtain the product.

7. The use according to claim 1, characterized in that: The mass ratio of the sulfonated EPDM rubber to the acrylonitrile-grafted EPDM rubber is 1:1-3.

8. The use according to claim 7, characterized in that The sulfonated EPDM rubber is prepared by the following steps: Dissolve EPDM rubber in n-heptane, then add concentrated sulfuric acid and acetic anhydride to the resulting solution, react at room temperature for 30 minutes, and then add ethanol to terminate the reaction; then add an ethanol solution of metal acetate, stir, flash evaporate to remove the solvent, and dry the residue at 100°C to obtain; The acrylonitrile grafted EPDM rubber is prepared by the following steps: Dissolve EPDM rubber in n-heptane, then add a xylene solution of azobisisobutyronitrile and a xylene solution of acrylonitrile in an inert gas atmosphere; after the reaction is complete, precipitate with acetone, and the resulting precipitate is Soxhlet extracted with N,N'-dimethylformamide and then vacuum-dried at 60°C to obtain the product.

9. The use according to claim 1, characterized in that The anti-scour material is prepared by the following steps: S1: dissolving the modified EPDM matrix material in a mixed solvent, then adding phenolic resin to the resulting solution and stirring to dissolve completely to obtain a glue solution; the mixed solvent is prepared by mixing n-heptane and ethyl acetate in a volume ratio of 2.5-5:2.5-4; the material-liquid ratio of the modified EPDM matrix material and phenolic resin to the mixed solvent is 0.5g:0.5g:4-6mL; S2: vacuum impregnation is used to evenly distribute the adhesive solution in the aramid fiber fabric to obtain an impregnated fabric; S3: volatilizing the mixed solvent in the impregnated fabric by ventilation drying, blowing or heating, thereby obtaining the fabric; the ventilation drying time is 6 to 10 hours, the blowing time is 2 to 3 hours, and the heating temperature is 40 to 60°C.

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