Modified carbon nitride speed reducer and application thereof in solid propellant

Abstract

The application belongs to the technical field of solid propellant, and relates to a modified carbon nitride speed-reducing agent and application thereof in solid propellant, application of the modified carbon nitride speed-reducing agent in double-base solid propellant, and application of the modified carbon nitride speed-reducing agent in hydroxyl-terminated solid propellant. The modified carbon nitride is obtained by mixing carbon nitride and fluorine-containing precursors and then high-temperature quenching treatment, and has good stability at normal temperature and pressure and can release a large amount of energy when combusting under pure oxygen condition. When the modified carbon nitride is used as a speed-reducing agent in solid propellant, the speed-reducing agent can reduce the burning rate and pressure index of the propellant, help to maintain or even improve the energy of the propellant, and significantly improve the mechanical properties of the propellant.

Description

Technical Field

[0001] This invention belongs to the field of solid propellant applications, and relates to a modified carbon nitride decelerator and its application in solid propellants. Background Technology

[0002] Solid propellants are the power source materials for solid rocket engines, playing a crucial role in the development of missile and aerospace technologies. They are generally classified into double-base propellants, composite propellants, modified double-base propellants, and NEPE propellants. As weaponry develops towards miniaturization, intelligence, long-range strike, and precision guidance, the tactical and technical specifications of weapons such as rocket endurance engines, missile and spacecraft attitude and orbit control engines, gas generators, and gun-launched rocket range extenders are becoming increasingly stringent. This leads to a growing demand for high-energy, low-burning-rate propellants (low thrust under high pressure, long endurance, and no reduction in specific impulse).

[0003] Currently, common methods for reducing propellant burning rate mainly focus on reducing system energy through decomposition and heat absorption, and inhibiting the combustion reaction of important propellant components. In the most widely used HTPB / AP / Al (hydroxyl-terminated polybutadiene / ammonium perchlorate / aluminum powder) composite solid propellant, the burning rate is mainly reduced by inhibiting the thermal decomposition of AP. Among them, ammonium oxalate ((NH4)2C2O4) has the advantages of good effect and low dosage, and the rate reduction effect is the most obvious (Shi Liangwei, Wu Yaming, Lü Long. Research on high-efficiency rate reducer of quaternary ammonium salt for HTPB propellant [J]. Solid Rocket Technology, 2023, 46(6):842-847.). In dual-base solid propellants, the initial decomposition temperature of the energetic components in the propellant is mainly affected by the endothermic effect of melting or decomposition, thereby changing the burning rate and pressure index of the propellant. The added deceleration agents mainly include polyoxymethylene (POM), sucrose octaacetate (SOA), polymethyl methacrylate (PMMA), etc. (Chen Yong, Zhao Fengqi, Li Hui, et al. Research status and development trend of solid propellant deceleration agents [J]. Journal of Explosives and Pyrotechnics, 2021, 44(5):567-577.). If AP is contained, urea, melamine, lithium fluoride, quaternary ammonium salts and other deceleration agents can be added to inhibit the thermal decomposition of the oxide ammonium perchlorate (AP) and thus reduce the burning rate. Low burning rate (Zhang Guohui, Zhao Fengqi, Xu Siyu, et al. Research progress on control technology for low burning rate of dual-base propellants [J]. Journal of Ordnance Equipment Engineering, 2021, 42(12):16-22.); however, in modified dual-base propellants containing a large amount of high-energy solid materials, these decelerators will significantly reduce the system energy and specific impulse because they do not contain energy themselves. At the same time, the amount of decelerator added and the deceleration effect will be limited (Yang Libo, Zhou Rui. Influence of composite decelerators on the combustion performance of low burning rate propellants [J]. Journal of Explosives and Pyrotechnics, 2013, 36(6):70-73.), and will also have a negative impact on the mechanical properties of the propellant.

[0004] Graphitic carbon nitride (g-C3N4), a novel high-nitrogen polymer, possesses a planar two-dimensional sheet structure similar to graphene. It can be obtained by calcining nitrogen-rich precursors such as ammonia cyanide, urea, thiourea, melamine, and dicyandiamide. The preparation process is short, simple, yields high, and is inexpensive (Ma D, et al. Research development on graphitic carbon nitride and enhanced catalytic activity on ammonium perchlorate[J]. RSC Advances, 2021, 11, 5729.). It exhibits good chemical and thermal stability at room temperature and pressure (thermal decomposition temperature ~650℃). Furthermore, as a high-nitrogen material with a nitrogen content as high as 60.9%, g-C3N4 burns under pure oxygen conditions, releasing a large amount of energy, making it an excellent combustion rate catalyst for composite solid propellants.

[0005] Therefore, it is of great significance to develop a decelerator that can reduce the propellant burning rate while maintaining or even increasing the propellant energy and specific impulse. Summary of the Invention

[0006] To address the technical problems of poor stability and ineffective deceleration of existing solid propellants under normal temperature and pressure, which are detrimental to the mechanical properties of the propellant, this invention provides a modified carbon nitride decelerator and its application in solid propellants.

[0007] This invention mixes calcined melamine with a fluorine-containing precursor, and then quenches it at high temperature and ball mills it to obtain modified graphitic carbon nitride. It has good stability at room temperature and pressure, and can release a large amount of energy when burned in pure oxygen. When modified carbon nitride is used as a decelerator in solid propellants, it helps to maintain or even increase the propellant energy and specific impulse while reducing the propellant burning rate and pressure index, and can also improve the mechanical properties of the propellant.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A modified carbon nitride decelerator and its application in solid propellants

[0010] Further specified, the mass of the modified carbon nitride decelerator is 0.4% to 1.2% of the total mass of the dual-base solid propellant; the burning rate of the dual-base solid propellant is 6.96 mm / s to 9.16 mm / s; and the pressure index of the dual-base solid propellant is 0.03 to 0.07.

[0011] Application of a modified carbon nitride decelerator in hydroxyl-butyl solid propellant.

[0012] Further specified, the mass of the modified carbon nitride decelerator is 0.5% of the total mass of the hydroxyl-butyl solid propellant; the pressure index of the hydroxyl-butyl solid propellant is 0.29.

[0013] The preparation method of the modified carbon nitride decelerator as described above is as follows:

[0014] S1. Melamine was directly calcined to obtain graphite carbon nitride powder A;

[0015] S2. The powder A obtained in step S1 is mixed with the fluorine-containing precursor at a mass ratio of 100:(1-9), and then dried, quenched at high temperature, and ball-milled to obtain the modified carbon nitride decelerator.

[0016] Further specifying, the calcination conditions in step S1 are: temperature 550℃, calcination time 4h, and heating rate 5.0℃·min. -1 .

[0017] Further specifying, the fluorinated precursor in step S2 is polyvinylidene fluoride, perfluoropolyether, or polytetrafluoroethylene.

[0018] Further specifying, the high-temperature quenching conditions are: temperature 300℃~550℃, time 2h~4h, and heating rate 2.5℃·min. -1 ~10.0℃·min -1 .

[0019] Further specified, the particle size of the target sample is 1μm to 2μm.

[0020] The beneficial effects of this invention are:

[0021] 1. The present invention further mixes carbon nitride with a fluorine-containing precursor and then quenches it to obtain modified carbon nitride, which has good stability at room temperature and pressure and can release a large amount of energy when burned under pure oxygen conditions. When modified carbon nitride is used as a decelerator in solid propellants, it helps to maintain or even improve the propellant energy and specific impulse while reducing the propellant burning rate and pressure index.

[0022] 2. The modified carbon nitride provided by this invention has a simple synthesis route, high yield, and good compatibility with various propellant components. It can effectively reduce the impact on propellant solidification and improve the mechanical properties of solid propellants. It has broad application prospects in various dual-base solid propellants and hydroxyl-butadiene solid propellants.

[0023] 3. This invention uses melamine, which is widely available and inexpensive. The powder obtained after calcining melamine is mixed with a fluorine-containing precursor and then subjected to high-temperature quenching to produce carbon materials, which can greatly reduce the cost of deceleration agents and reduce the cost of solid propellants.

[0024] 4. The modified carbon nitride decelerator product prepared by this invention replaces the carbon black commonly used in solid propellants. Under the condition that the contents of other components remain unchanged, it has a significant deceleration effect on a variety of dual-base solid propellants. The burning rate of dual-base solid propellants is 6.96 mm / s to 9.16 mm / s at 6 MPa, and the pressure index is 0.03 to 0.07. Therefore, it has great application potential in slow-burning solid propellants with low pressure and low burning rate.

[0025] 5. The modified carbon nitride prepared by this invention can replace the ammonium oxalate decelerator commonly used in hydroxyl-butyl solid propellants as a decelerator, which can significantly increase the propellant density and improve the mechanical properties of the propellant. Attached Figure Description

[0026] Figure 1 XRD pattern of the modified graphitic carbon nitride prepared in Example 1;

[0027] Figure 2 The infrared spectrum of the modified graphitic carbon nitride prepared in Example 1;

[0028] Figure 3 The image shows a SEM image of the modified graphitic carbon nitride prepared in Example 1. Detailed Implementation

[0029] The technical solution provided by this invention will be described in detail below. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art.

[0030] The terminology used in this invention is for the purpose of describing specific implementations only and should not be construed as limiting the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0031] This invention provides an application of a modified graphitic carbon nitride decelerator in a dual-base solid propellant system.

[0032] Preferably, under the condition that the contents of other components remain unchanged, the mass of the modified carbon nitride decelerator is 0.4% to 1.2% of the total mass of the dual-base solid propellant; the burning rate of the dual-base solid propellant is

[0033] 6.96 mm / s to 9.16 mm / s; the pressure index of the double-base solid propellant is 0.03 to 0.07.

[0034] This invention also provides the application of a modified carbon nitride decelerator in hydroxyl-butyl solid propellants.

[0035] Preferably, under the condition that the contents of other components remain unchanged, the mass of the modified carbon nitride decelerator is 0.5% of the total mass of the hydroxyl-butyl solid propellant; the pressure index of the hydroxyl-butyl solid propellant is 0.29.

[0036] This invention also provides a modified carbon nitride decelerator, the specific preparation method of which is as follows:

[0037] S1. Melamine is directly calcined to obtain carbon nitride powder A; the calcination is carried out using a method commonly used in this industry. The calcination conditions in step S1 of this invention are: temperature 550℃, calcination time 4h, and heating rate 5.0℃·min. -1 .

[0038] S2. The powder A obtained in step S1 is mixed with the fluorine-containing precursor at a mass ratio of 100:(1-9), and then dried, quenched at high temperature, and ball-milled to obtain the target sample.

[0039] In step S2 of this invention, the mixing mass ratio of powder A and the fluorine-containing precursor is 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8 or 100:9.

[0040] In step S2 of this invention, the fluorinated precursor is one of polyvinylidene fluoride (PVDF), perfluoropolyether (PFPE), and polytetrafluoroethylene (PTFE).

[0041] The high-temperature quenching conditions in step S2 of this invention are: temperature 300℃~550℃, time 2h~4h, and heating rate 2.5℃·min. -1 ~10.0℃·min -1 .

[0042] The target sample prepared in step S2 of this invention has a particle size of 1μm to 2μm.

[0043] To facilitate understanding of the present invention, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] It should be noted that, unless otherwise specified, the operations referred to in the following embodiments are all conventional operations in the art, such as stirring, mixing, drying, calcining, etc.

[0045] It should be noted that, unless otherwise specified, the medicines and reagents used in the following examples are all raw materials purchased from the market.

[0046] Example 1

[0047] The application of the modified carbon nitride decelerator in solid propellants provided in this embodiment.

[0048] Preferably, the solid propellant is a dual-base solid propellant, or it can be a hydroxyl-butadiene solid propellant.

[0049] The modified carbon nitride decelerator used in this embodiment is prepared by the following steps:

[0050] 1) Weigh 100g of melamine and place it in a muffle furnace, heating at 5.0℃·min -1 The mixture was heated to 550℃ and calcined for 4 hours to obtain yellow powder A.

[0051] 2) Take 10g of powder A and 0.1g of polyvinylidene fluoride (PVDF), physically mix them, and place them in a muffle furnace at 2.5℃·min. -1 The temperature was raised to 500℃ and calcined for 2 hours to obtain a light yellow powder B. Finally, the light yellow powder B was ball-milled in a ball mill to obtain a modified carbon nitride decelerator with a particle size of 1μ~2μm, which is designated as product 1.

[0052] Example 2

[0053] The modified graphitic carbon nitride decelerator provided in this embodiment is used in solid propellants.

[0054] Preferably, the solid propellant is a dual-base solid propellant, or it can be a hydroxyl-butadiene solid propellant.

[0055] The modified carbon nitride decelerator used in this embodiment is prepared by the following steps:

[0056] 1) Weigh 100g of melamine and place it in a muffle furnace, heating at 5.0℃·min -1 The mixture was heated to 550℃ and calcined for 4 hours to obtain yellow powder A.

[0057] 2) Take 10g of powder A and 0.3g of polyvinylidene fluoride (PVDF), physically mix them, and place them in a muffle furnace at 2.5℃·min. -1 The temperature was raised to 500℃ and calcined for 2 hours to obtain a light yellow powder B. Finally, the light yellow powder B was ball-milled in a ball mill to obtain a modified carbon nitride decelerator with a particle size of 1μ~2μm, which is designated as product 2.

[0058] Example 3

[0059] The application of graphitic carbon nitride decelerator in solid propellants provided in this embodiment.

[0060] Preferably, the solid propellant is a dual-base solid propellant, or it can be a hydroxyl-butadiene solid propellant.

[0061] The modified carbon nitride decelerator used in this embodiment is prepared by the following steps:

[0062] 1) Weigh 100g of melamine and place it in a muffle furnace, heating at 5.0℃·min -1 The mixture was heated to 550℃ and calcined for 4 hours to obtain yellow powder A.

[0063] 2) Take 10g of powder A and 0.5g of polyvinylidene fluoride (PVDF), physically mix them, and place them in a muffle furnace at 2.5℃·min. -1 The temperature was raised to 500℃ and calcined for 2 hours to obtain a light yellow powder B. Finally, the light yellow powder B was ball-milled in a ball mill to obtain a modified carbon nitride decelerator with a particle size of 1μ~2μm, which is designated as product 3.

[0064] Example 4

[0065] The application of the modified carbon nitride decelerator in solid propellants provided in this embodiment.

[0066] Preferably, the solid propellant is a dual-base solid propellant, or it can be a hydroxyl-butadiene solid propellant.

[0067] The modified carbon nitride decelerator used in this embodiment is prepared by the following steps:

[0068] 1) Weigh 100g of melamine and place it in a muffle furnace, heating at 5.0℃·min -1 The mixture was heated to 550℃ and calcined for 4 hours to obtain yellow powder A.

[0069] 2) Take 10g of powder A and 0.7g of polyvinylidene fluoride (PVDF), physically mix them, and place them in a muffle furnace at 2.5℃·min. -1 The temperature was raised to 500℃ and calcined for 2 hours to obtain a light yellow powder B. Finally, the light yellow powder B was ball-milled in a ball mill to obtain a modified carbon nitride decelerator with a particle size of 1μ~2μm, which is designated as product 4.

[0070] Example 5

[0071] The application of the modified carbon nitride decelerator in solid propellants provided in this embodiment.

[0072] Preferably, the solid propellant is a dual-base solid propellant, or it can be a hydroxyl-butadiene solid propellant.

[0073] The modified carbon nitride decelerator used in this embodiment is prepared by the following steps:

[0074] 1) Weigh 100g of melamine and place it in a muffle furnace, heating at 5.0℃·min -1 The mixture was heated to 550℃ and calcined for 4 hours to obtain yellow powder A.

[0075] 2) Take 10g of powder A and 0.9g of polyvinylidene fluoride (PVDF), physically mix them, and place them in a muffle furnace at 2.5℃·min.-1 The temperature was raised to 500℃ and calcined for 2 hours to obtain a light yellow powder B. Finally, the light yellow powder B was ball-milled in a ball mill to obtain a modified carbon nitride decelerator with a particle size of 1μ~2μm, which is designated as product 5.

[0076] To further demonstrate the performance of the modified carbon nitride decelerator prepared in this invention in solid propellants, the following verification experiments were conducted.

[0077] Experiment 1

[0078] The modified carbon nitride decelerator from Example 1 was used, and its XRD, infrared spectrum, and SEM images were measured. The results are as follows: Figure 1 , Figure 2 and Figure 3 As shown.

[0079] from Figures 1-3 It can be seen that the modified carbon nitride decelerator has been successfully prepared.

[0080] Experiment 2

[0081] The modified carbon nitride prepared in Example 1 was applied to the modified double-base solid propellant (formulation 1) in Table 1 for burning rate testing, and the test results were compared with those of the formulation with added carbon black CB.

[0082] Table 1 Components of Modified Double-Base Solid Propellant (Formula 1)

[0083] Formula composition Content / wt% Component 1 NC (Nitrocellulose) + NG (Nitroglycerin) 41.2 Component 2 RDX (Hexagonal Gold) 50.0 Component 3 Functional components 8.8

[0084] Table 1 lists functional components including lead salts, copper salts, decelerating agents, methyl stabilizers, petrolatum, and other ingredients used in the formulation to increase stability, adjust material friction, regulate combustion performance, and act as ballistic stabilizers. The lead salts are β-Pb or NTO-Pb, and the copper salts are β-Cu or CuO.

[0085] The types and contents of lead salts, copper salts and decelerating agents in the above functional components are detailed in Table 2; the total content of the remaining components is 3.8 wt%, but the specific content of each component is not specified in detail.

[0086] Table 2. Types and contents of functional components

[0087]

[0088] According to the raw materials and content ratios of each group in Tables 1 and 2, six groups of modified double-base solid propellants were formed. Then, the burning rate and pressure index of the modified double-base solid propellants were measured under different pressures, and the results are shown in Table 3.

[0089] Table 3 Burning rate and pressure index of different groups of modified double-base solid propellants

[0090]

[0091] As shown in Table 3, with other components remaining constant, using the modified carbon nitride prepared in Example 1 as a rate-reducing agent, the burning rate of the dual-base solid propellant was 6.96 mm / s to 9.16 mm / s under pressures of 2 MPa to 6 MPa, and the pressure index was 0.03 to 0.07. The experimental data indicate that for dual-base solid propellants with different types of lead-copper salt catalysts, the modified graphite carbon nitride prepared in Example 1 achieved a significant rate-reducing effect in the low-pressure stage, lowering the pressure index to 0.03. Modified graphite carbon nitride has significant application potential in low-pressure, low-burning-rate slow-burning propellants.

[0092] Experiment 3

[0093] The purpose of this experiment is to apply the modified carbon nitride prepared in Example 2 as a decelerator in the solid propellant (formulation 2) of a certain type of gas generator as shown in Table 4 (mainly NC and NG dual-base components, containing a small amount of aluminum powder), and to compare it with the formulation containing carbon black CB.

[0094] Table 4 Composition of solid propellant (Formula 2)

[0095] Formula composition Content / wt% Component 1 NC (Nitrocellulose) + NG (Nitroglycerin) 89.3 Component 2 Al powder 2.9 Component 3 Functional components 7.8

[0096] Table 4 lists functional components such as lead salts, copper salts, decelerators, methyl stabilizers, and petrolatum, which are used in the formulation to increase stability, adjust material friction, regulate combustion performance, and act as ballistic stabilizers.

[0097] The deceleration agents used were modified carbon nitride (experimental group) and carbon black (control group) prepared in Example 2, and the content of the deceleration agents is shown in Table 5. The total content of the remaining components was 6.9 wt%. After forming solid propellants, the burning rate of the solid propellants was measured under different pressures, and the results are shown in Table 5.

[0098] Table 5 Burning rate of solid propellant in a certain type of gas generator

[0099]

[0100] As can be seen from the burning rate test data under different pressures in Table 5, the modified carbon nitride in this embodiment can significantly reduce the burning rate of the solid catalyst in the low pressure (2MPa~6MPa), medium pressure (6MPa~14MPa) and high pressure (14MPa~20MPa) ranges after replacing carbon black.

[0101] Experiment 4

[0102] The purpose of this experiment is to apply the modified carbon nitride prepared in Example 3 as a decelerator to a mature high-energy, low-signal solid propellant (formulation 3) of a certain type of rocket propellant as shown in Table 6 (mainly NC and NG dual-base components, containing a high content of RDX), and to compare it with the formulation with added carbon black CB.

[0103] Table 6 Composition of solid propellant (Formula 3)

[0104]

[0105] Table 6 lists functional components such as lead salts, copper salts, decelerators, methyl stabilizers, and petrolatum, which are used in the formulation to increase stability, adjust material friction, regulate combustion performance, and act as ballistic stabilizers.

[0106] In the functional components, the deceleration agents were modified carbon nitride (experimental group) and carbon black (control group) prepared in Example 3, and the content of the deceleration agents is shown in Table 7. The total content of the remaining components in the functional components was 3.5 wt%. After forming solid propellant, the burning rate of solid propellant was measured under different pressures, and the results are shown in Table 7.

[0107] Table 7 Burning rate of solid propellant in a certain type of gas generator

[0108]

[0109] As can be seen from the burning rate test data under different pressures in Table 7, after the modified carbon nitride replaces carbon black in this embodiment, the burning rate of the solid catalyst in the range of low pressure (2MPa~6MPa), medium pressure (6MPa~14MPa) and high pressure (14MPa~20MPa) can be significantly reduced.

[0110] Experiment 5

[0111] The purpose of this experiment is to apply the modified carbon nitride prepared in Example 3 as a decelerator to the hydroxyl-butyl solid propellant (formulation 4) propellant (mainly HTPB, AP, RDX, and aluminum powder) shown in Table 8, and to compare it with the blank formulation and the formulation with added ammonium oxalate.

[0112] Table 8 Composition of solid propellant (Formula 4)

[0113]

[0114] The burn rate regulator (also known as the decelerator) used was modified carbon nitride prepared in Example 3 (experimental group), and the decelerator content is shown in Table 9. It was compared with no decelerator (control group 1) and ammonium oxalate as decelerator (control group 2). In the experimental group, control group 1 and control group 2, the content of the remaining components in component 4 was determined according to the decelerator content, forming three groups of hydroxyl-butyl solid propellants.

[0115] Furthermore, the density, burning rate, pressure index, and mechanical properties at different temperatures of the three groups of hydroxyl-butyl solid propellants were measured under different pressures. The results are shown in Table 9.

[0116] Table 9 Performance parameters of hydroxyl-butyl solid propellant

[0117]

[0118] As can be seen from the mechanical property data at different temperatures in Table 9, the modified carbon nitride in Example 3, which replaced ammonium oxalate, can significantly improve the mechanical properties of hydroxyl-butyl solid propellant. At the same time, the pressure index of hydroxyl-butyl solid propellant is 0.29 under pressures of 4 MPa to 13 MPa, which is a decrease. In addition, compared with no decelerator (comparative group 1), the use of modified carbon nitride as a decelerator can reduce the burning rate of hydroxyl-butyl solid propellant at 7 MPa.

[0119] The above experiments show that the modified carbon nitride prepared by mixing carbon nitride with fluoride, followed by high-temperature quenching and ball milling, can be added as a deceleration agent to various dual-base solid propellant formulations. This method achieves significant deceleration effects in low-pressure, medium-pressure, and high-pressure stages, and reduces the pressure index of solid propellants in the low-pressure stage. It has great potential for future application in low-pressure, low-burning-rate slow-burning propellants. Furthermore, replacing ammonium oxalate in equal amounts in hydroxyl-butyl propellants can improve the mechanical properties of the propellant and increase its density.

[0120] The above description only illustrates several embodiments of the present invention, but should not be construed as limiting the scope of protection of the claims of the present invention; any equivalent substitutions and modifications made based on the technology disclosed in the present invention should fall within the protection scope of the present invention.

Claims

1. The application of a modified carbon nitride decelerator in a dual-base solid propellant system, characterized in that, The preparation method of the modified carbon nitride decelerator is as follows: S1. Melamine is directly calcined to obtain carbon nitride powder A; S2. The powder A obtained in step S1 is mixed with the fluorine-containing precursor at a mass ratio of 100:(1~9), and then dried, quenched at high temperature and ball-milled to obtain the modified carbon nitride decelerator. In step S2, the fluorinated precursor is polyvinylidene fluoride, perfluoropolyether, or polytetrafluoroethylene.

2. The application according to claim 1, characterized in that, The modified carbon nitride decelerator accounts for 0.4% to 1.2% of the total mass of the dual-base solid propellant; the burning rate of the dual-base solid propellant is 6.96 mm / s to 9.16 mm / s; and the pressure index of the dual-base solid propellant is 0.03 to 0.

07.

3. The application of a modified carbon nitride decelerator in hydroxyl-butyl solid propellant, characterized in that, The preparation method of the modified carbon nitride decelerator is as follows: S1. Melamine is directly calcined to obtain carbon nitride powder A; S2. The powder A obtained in step S1 is mixed with the fluorine-containing precursor at a mass ratio of 100:(1~9), and then dried, quenched at high temperature and ball-milled to obtain the modified carbon nitride decelerator. In step S2, the fluorinated precursor is polyvinylidene fluoride, perfluoropolyether, or polytetrafluoroethylene.

4. The application according to claim 3, characterized in that, The modified carbon nitride decelerator has a mass of 0.5% of the total mass of the hydroxyl-butyl solid propellant; the pressure index of the hydroxyl-butyl solid propellant is 0.

29.

5. The application according to claim 1 or 3, characterized in that, The calcination conditions in step S1 are: temperature 550℃, calcination time 4h, and heating rate 2.5℃•min. -1 .

6. The application according to claim 5, characterized in that, The high-temperature quenching conditions in step S2 are: temperature 300℃~550℃, time 2h~4h, and heating rate 2.5℃•min. -1 ~10.0℃•min -1 .

7. The application according to claim 5, characterized in that, The particle size of the modified carbon nitride decelerator in step S2 is 1μm~2μm.

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