Composite flame suppressant and method for preparing the same
By using KN3 and DAP-2 as primary and secondary flame suppressants, and combining them with NC, GAP, DGTN and potassium stearate as coating agents, the problems of potassium salts being hygroscopic and having low energy were solved, achieving a high-energy, low-hygroscopic flame suppressing effect, which is suitable for solid propellants.
Patent Information
- Application Number
- CN202311775450.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-12-26
- Estimated Expiration
- 2043-12-22
AI Technical Summary
The potassium salts used in existing solid propellants are inert and hygroscopic, which leads to a decrease in the energy performance of the propellant and cannot effectively suppress secondary combustion.
A composite flame smother was prepared by using KN3 and DAP-2 as primary and secondary flame smothers, and by using NC, GAP, DGTN and potassium stearate as coating agents to reduce their hygroscopicity and sensitivity. The composite flame smother consisted of 50-60% KN3, 37-47% DAP-2, 20-35% NC, 20-35% GAP, 35-50% DGTN and 5-15% potassium stearate.
It improves the energy performance of the propellant, reduces secondary combustion, is not easily hygroscopic, has a good flame extinguishing effect, and is suitable for large-scale production.
Smart Images
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of composite solid propellant combustion flame inhibitor, in particular to a composite flame inhibitor for solid propellant and a preparation method thereof. BACKGROUND
[0002] In the process of solid propellant combustion, the gas products discharged from the nozzle of the rocket engine are mainly CO2, H2O, HCl, N2, CO and H2, wherein the molar fraction of CO and H2 accounts for more than half of the total combustion products. These high-temperature CO and H2 gases will mix with atmospheric oxygen and burn violently to generate CO2 and H2O, and release a large amount of heat, resulting in strong visible light radiation and infrared radiation of the propellant plume, which is called secondary combustion of the propellant. The secondary combustion phenomenon will cause many hazards. For example, ① the secondary combustion will cause the launch platform to be exposed, affecting the survivability of the missile weapon system; ② the secondary combustion will cause the guidance radar wave to attenuate; ③ the secondary combustion will cause the noise of the rocket engine to increase; ④ the secondary combustion produces strong light, which will cause the launch personnel to be visually blind. Therefore, reducing the plume characteristic signals of the engine is crucial for the stealth of the missile, and reducing the plume characteristic signals is the key to studying low characteristic signal propellants. In order to suppress the secondary combustion of the solid rocket engine and reduce the plume characteristic signals, currently, 2-3% of potassium salt is added to the propellant formula to reduce the secondary combustion, such as K2SO4, KNO3, KClO4, K2CO3 or K3AlF6 inorganic or organic potassium salt. The gaseous KOH generated by the potassium salt during the combustion of the propellant greatly suppresses and blocks the combustion reaction of CO and H2 in the gas with oxygen, thereby avoiding the secondary combustion phenomenon of the propellant.
[0003] However, the potassium salt currently used is basically inert, that is, it does not contain energy, and it is hygroscopic. The application of these non-energy-containing potassium salts to the propellant will reduce the specific impulse and thrust of the propellant, resulting in deterioration of the energy performance of the propellant. Therefore, it is of great significance to develop energy-containing potassium salt and apply it to the solid propellant. SUMMARY
[0004] In view of the deficiencies of the prior art, the present application provides a composite flame inhibitor for solid propellant, which solves the problems of low energy of existing gas generating agent and easy moisture absorption.
[0005] To achieve the above object, the present application is implemented by the following technical scheme:
[0006] The present application discloses a composite flame inhibitor for solid propellant, which comprises KN3 50-60%, DAP-2 37-47%, and the balance of NC, GAP, DGTN and potassium stearate in terms of mass percentage.
[0007] Preferably, the NC is 20-35%, the GAP is 20-35%, the DGTN is 35-50%, and the potassium stearate is 5-15% by mass percentage.
[0008] Correspondingly, a preparation method of the composite flame inhibitor, the NC, the GAP, the DGTN and the potassium stearate are added into ethyl acetate, and after being dissolved, the adhesive solution is sealed; the KN3 and the DAP-2 are mixed and then added into the adhesive solution, stirred, and dried to obtain the composite flame inhibitor.
[0009] Preferably, the mixing time of the KN3 and the DAP-2 is 0.5-1.5 h.
[0010] Preferably, the drying temperature is 50-65 ℃, and the time is 20-32 h.
[0011] The present application has the following advantages:
[0012] 1. The energy of the primary and secondary flame inhibitors used in the present application is high, and after being used in the propellant, the energy is higher than that of the commonly used flame inhibitors K2SO4 and KNO3. Moreover, the flame inhibition effect is good, which is better than that of the commonly used flame inhibitors K2SO4 and KNO3, and the flame inhibitor can be stored for a long time without deterioration and moisture absorption.
[0013] 2. The raw materials involved in the present application have low cost and simple preparation process, and have the basis for large-scale production. DETAILED DESCRIPTION
[0014] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.
[0015] If not specifically indicated, the technical means used in the examples is the conventional means known to those skilled in the art.
[0016] The present application finds that potassium azide (KN3) and the molecular perovskite energetic material DAP-2 (molecular formula: (H2dabco) [K(ClO4)3] or (C6H 14N2) [K(ClO4)3]) are two very good high-energy potassium salts. Among them, the preparation method and performance of DAP-2 are seen in the literature (Shao-Li Chen, Zi-Run Yang, Bin-Jie Wang, et al. Molecular perovskite high-energetic materials [J]. Science China Materials, 2018, 61(8): 1123-1128.), KN3 and DAP-2 have very high energy and high potassium content. Among them, the potassium content of KN3 is 48.1%, and the potassium content of DAP-2 is 8.7%. In particular, KN3, the potassium content has exceeded the potassium content (44.9%) of K2SO4, and its flameout effect is very good, which is an ideal choice to replace the currently used potassium-free salt. At present, there is no report on the application of KN3 and DAP-2 as solid propellant flameout agent.
[0017] 1. The present application discloses a composite flameout agent, which comprises KN3 50-60%, DAP-2 37-47%, and the balance of NC, GAP, DGTN and potassium stearate in terms of mass percentage.
[0018] Among them, KN3 is the main flameout agent, DAP-2 is the auxiliary flameout agent, and [NC+GAP+DGTN+potassium stearate] is the coating agent. In the coating agent [NC+GAP+DGTN+potassium stearate], NC accounts for 20-35%, GAP accounts for 20-35%, DGTN accounts for 35-50%, and potassium stearate accounts for 5-15% in terms of mass percentage. The role of the coating agent is to reduce the hygroscopicity and sensitivity of KN3 and DAP-2 under the premise of ensuring energy performance. In the coating agent, NC, GAP and DGTN are all high-energy substances, which can not only improve the energy, but also reduce the sensitivity and hygroscopicity of the main and auxiliary flameout agents. In the coating agent, potassium stearate is a potassium salt, which not only has the functions of preventing moisture absorption and preventing caking, but also can play a certain flameout effect.
[0019] 2. The present application also discloses a preparation method of the composite flameout agent. NC, GAP, DGTN and potassium stearate are added to ethyl acetate, dissolved and sealed to obtain an adhesive solution; KN3 and DAP-2 are mixed and then added to the adhesive solution, stirred, dried, and sieved through a 80-120 mesh screen to obtain the composite flameout agent.
[0020] Among them, the mixing time of KN3 and DAP-2 is 0.5-1.5 h. The drying temperature is 50-65°C, and the time is 20-32 h.
[0021] The present application will be further described below in combination with specific examples.
[0022] Example 1
[0023] The composite flame inhibitor includes K2SO4: 50%; KNO3: 47%; NC: 0.75%; GAP: 0.75%; DGTN: 1.2%; and potassium stearate: 0.3% by mass.
[0024] The preparation process is as follows: 0.75 g of NC, 0.75 g of GAP, 0.12 g of DGTN and 0.3 g of potassium stearate are weighed and added to a beaker containing 50 mL of ethyl acetate. After all the substances are completely dissolved, the beaker is sealed with plastic wrap to obtain a binder solution for later use. 50 g of K2SO4 and 47 g of KNO3 are weighed and placed in a small low-speed anti-static rotary mixer. After 1 h of mixing, the mixer is stopped and the mixture is taken out. The mixture of K2SO4 and KNO3 is added to the beaker containing the binder solution and stirred into a thin paste. Then, the thin paste is scooped out with a spoon into a stainless steel tray, and the tray is placed in a water bath oven. The temperature of the water bath oven is set to 55°C, and after drying for 24 h, the product is sieved through an 80-mesh screen to obtain the composite flame inhibitor. The composite flame inhibitor prepared in Example 1 is added to a composite modified double-base propellant (CMDB), and the formula of the propellant is shown in Table 1.
[0025] Table 1. Formula of a solid propellant (CMDB-1) using the product prepared in Example 1 as a flame inhibitor
[0026] Propellant components Mass percent Nitrocellulose (NC) 21％ Nitroglycerine (NG) 21％ Aluminum powder (Al) 5％ Ammonium perchlorate (AP) 5％ Hexogen (RDX) 45％ Composite flame suppressant prepared in Example 1 3％
[0027] Comparative Example 1
[0028] The composite flame inhibitor includes K2SO4: 50%; KNO3: 47%; NC: 0.75%; GAP: 0.75%; DGTN: 1.2%; and potassium stearate: 0.3% by mass.
[0029] The preparation process is as follows: 0.75 g of NC, 0.75 g of GAP, 0.12 g of DGTN and 0.3 g of potassium stearate are weighed and added to a beaker containing 50 mL of ethyl acetate. After all the substances are completely dissolved, the beaker is sealed with plastic wrap to obtain a binder solution for later use. 50 g of K2SO4 and 47 g of KNO3 are weighed and placed in a small low-speed anti-static rotary mixer. After 1 h of mixing, the mixer is stopped and the mixture is taken out. The mixture of K2SO4 and KNO3 is added to the beaker containing the binder solution and stirred into a thin paste. Then, the thin paste is scooped out with a spoon into a stainless steel tray, and the tray is placed in a water bath oven. The temperature of the water bath oven is set to 55°C, and after drying for 24 h, the product is sieved through an 80-mesh screen to obtain the composite flame inhibitor. The composite flame inhibitor prepared in Example 1 is added to a composite modified double-base propellant (CMDB), and the formula of the propellant is shown in Table 1.
[0030] Table 2 Solid propellant formulation (CMDB-2) with product prepared in Comparative Example 1 as flame inhibitor
[0031]
[0032]
[0033] Example 2
[0034] The composite flame inhibitor includes, by mass percent, KN3: 60%; DAP-2: 37%; NC: 0.75%; GAP: 0.75%; DGTN: 1.2%; and potassium stearate: 0.3%.
[0035] The preparation process is as follows: 0.75 g of NC, 0.75 g of GAP, 0.12 g of DGTN, and 0.3 g of potassium stearate are weighed and added to a beaker containing 50 mL of ethyl acetate. After all the substances are completely dissolved, the beaker is sealed with plastic wrap to obtain an adhesive solution, which is ready for use. 60 g of KN3 and 37 g of DAP-2 are placed in a small low-speed anti-static rotary mixer. After mixing for 1 h, the mixer is stopped and the mixture is removed. The mixture of KN3 and DAP-2 is added to the beaker containing the adhesive solution and stirred into a thin paste. Then, the thin paste is scooped out with a spoon into a stainless steel tray, and the tray is placed in a water bath oven. The temperature of the water bath oven is set to 55°C, and after drying for 24 h, the composite flame inhibitor is obtained by passing through an 80-mesh screen. The composite flame inhibitor prepared in Example 2 is added to a composite modified double-base propellant (CMDB), and the formulation of the propellant is shown in Table 3.
[0036] Table 3 Solid propellant formulation (CMDB-3) with product prepared in Example 2 as flame inhibitor
[0037] Propellant components Mass percent Nitrocellulose (NC) 21％ Nitroglycerine (NG) 21％ Aluminum powder (Al) 5％ Ammonium perchlorate (AP) 5％ Hexogen (RDX) 45％ Composite flame suppressant prepared in Example 2 3％
[0038] Comparative Example 2
[0039] The composite flame inhibitor includes, by mass percent, K2SO4: 60%; KN3: 37%; NC: 0.75%; GAP: 0.75%; DGTN: 1.2%; and potassium stearate: 0.3%.
[0040] The preparation process is as follows: 0.75 g of NC, 0.75 g of GAP, 0.12 g of DGTN and 0.3 g of potassium stearate are weighed and added to a beaker containing 50 mL of ethyl acetate. After all the materials are completely dissolved, the beaker is sealed with plastic wrap to obtain an adhesive solution, which is ready for use. 60 g of K2SO4 and 37 g of KNO3 are weighed and placed in a small low-speed anti-static rotary mixer. After mixing for 1 h, the mixture is removed. The mixture of K2SO4 and KNO3 is added to the beaker containing the adhesive solution and stirred into a thin paste. Then, the thin paste is scooped out with a spoon into a stainless steel tray, and the tray is placed in a water bath oven. The temperature of the water bath oven is set to 55°C, and after drying for 24 h, the product is sieved through an 80-mesh screen to obtain a composite flame retardant. The composite flame retardant prepared in Comparative Example 2 is added to a composite modified double-base propellant (CMDB). The formulation of the propellant is shown in Table 4.
[0041] Table 4 Formulation of solid propellant using the product prepared in Comparative Example 2 as a flame retardant (CMDB-4)
[0042] Propellant components Mass percent Nitrocellulose (NC) 21％ Nitroglycerine (NG) 21％ Aluminum powder (Al) 5％ Ammonium perchlorate (AP) 5％ Hexogen (RDX) 45％ Composite flame suppressant prepared in Example 3 3％
[0043] Comparative Example 3
[0044] The propellant formulation without a flame retardant is shown in Table 5.
[0045] Table 5 Formulation of solid propellant without a flame retardant (CMDB-5)
[0046] Propellant components Mass percent Nitrocellulose (NC) 21％ Nitroglycerine (NG) 21％ Aluminum powder (Al) 5％ Ammonium perchlorate (AP) 5％ Hexogen (RDX) Composite flame suppressant prepared in Comparative Example 2 Propellant components Mass percent Nitrocellulose (NC) Nitroglycerine (NG) Aluminum powder (Al) Ammonium perchlorate (AP) Hexogen (RDX) 48％
[0047] The energy performance (specific impulse and characteristic velocity), flame retardancy (secondary flame area) and hygroscopicity of the 5 groups of propellants involved in the present application are shown in Table 6.
[0048] Table 6 Performance of solid propellants using the products prepared in all examples and comparative examples as a flame retardant
[0049]
[0050]
[0051] As can be seen from Table 6, the propellant without the flame inhibitor (CMDB-5) has the highest performance, i.e. after adding 3% of the flame inhibitor, the energy of the four groups of propellants has a small amount of loss, which is inevitable. Among them, the propellant added with the flame inhibitor of Example 1 (CMDB-1) has higher specific impulse and characteristic velocity than the propellant added with the flame inhibitor of Comparative Example 1 (CMDB-2); the propellant added with the flame inhibitor of Example 2 (CMDB-3) has higher specific impulse and characteristic velocity than the propellant added with the flame inhibitor of Comparative Example 2 (CMDB-4). This shows that the energy performance of KN3 and DAP-2 is obviously higher than that of K2SO4 and KNO3.
[0052] In addition, the secondary flame area generated by the combustion of all the propellants added with the flame inhibitor is much lower than that of the propellant without the flame inhibitor (CMDB-5). This shows that the potassium salt has a significant inhibitory effect on the secondary flame generated by the combustion of this kind of propellant. The secondary flame area generated by the combustion of the CMDB-1 propellant is smaller than that of the CMDB-2 propellant; and the secondary flame area generated by the combustion of the CMDB-3 propellant is smaller than that of the CMDB-4 propellant. This shows that the flame inhibition effect of KN3 and DAP-2 is obviously higher than that of K2SO4 and KNO3.
[0053] In addition, the hygroscopicity of all the propellants added with the flame inhibitor of Example 1 and Example 2 (CMDB-1 and CMDB-3) is similar to that of the propellant without the flame inhibitor (CMDB-5); the hygroscopicity of all the propellants added with the flame inhibitor of Comparative Example 1 and Comparative Example 2 (CMDB-2 and CMDB-4) is higher than that of the propellant without the flame inhibitor (CMDB-5). This shows that after KN3 and DAP-2 are coated with [NC+GAP+DGTN+potassium stearate] in the present application, they have little hygroscopicity, while K2SO4 and KNO3 coated with [NC+GAP+DGTN+potassium stearate] still have a small amount of hygroscopicity.
[0054] The above-described examples only describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.
Claims
1. A composite flame suppressant, characterized by: According to the mass percentage, it comprises KN3 50-60%, DAP-2 37-47%, and the rest is coating agent; according to the mass percentage, the coating agent is composed of NC 20-35%, GAP 20-35%, DGTN 35-50% and potassium stearate 5-15%.
2. A method of preparing the composite flame suppressant of claim 1, characterized by: NC, GAP, DGTN and potassium stearate are added into ethyl acetate, dissolved, sealed to obtain an adhesive solution; KN3 and DAP-2 are mixed, added into the adhesive solution, stirred, and dried to obtain the composite flame retardant.
3. The method of claim 2, wherein: The mixing time of the KN3 and DAP-2 is 0.5-1.5 h.
4. The method of claim 2, wherein: The drying temperature is 50-65 DEG C, and the time is 20-32 h.