Low-sensitivity graphene coated CL-20 composite material and preparation method thereof

Abstract

The invention discloses a low-sensitivity graphene coated CL-20 composite material and a preparation method thereof, and the method comprises the following steps: ultrasonically dispersing a graphene material in a solvent A to obtain a graphene dispersion liquid I; weighing CL-20 and a surface modifier according to a certain ratio, adding the CL-20 and the surface modifier into the graphene dispersion liquid I, and stirring to enable the CL-20 to fully adsorb the graphene material; weighing a coating agent, dissolving the coating agent in a solvent B to obtain a coating liquid II, dropwise adding the coating liquid II into the graphene dispersion liquid I at a certain stirring speed, keeping a certain temperature, separating out the coating agent from the mixed liquid in the dropwise adding process of the coating liquid II, coating the surfaces of solid particles with the coating agent, continuously stirring to react for a certain time after dropwise adding is completed, and then filtering, cleaning and drying to obtain the graphene composite material. The low-sensitivity graphene coated CL-20 composite material is obtained. The CL-20 composite material is simple in preparation method, stable in product and low in coating amount, the sensitivity of the CL-20 composite material is obviously reduced compared with that of a CL-20 raw material, and the application safety of the CL-20 composite material can be greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of energetic materials. Background Art

[0002] Hexanitrohexaazaisowurtzitane (CL-20) is a compound with a cage-like, polynitropolycyclic nitramine structure. It is a new type of high-energy compound with great potential due to its large ring tension, high crystal density and good stability. The inventors have found through research that the main problem that currently hinders the application of CL-20 in solid propellants, explosives and propellants is that its sensitivity is still relatively high (relative to traditional energetic substances). Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the first aspect of the present invention provides a method for preparing a low-sensitivity graphene-coated CL-20 composite material. The preparation method is simple, the product is stable, the coating amount is low, and the sensitivity is significantly reduced compared with the CL-20 raw material, which can greatly improve the application range of the material.

[0004] The technical solution adopted by the present invention is as follows: A method for preparing a low-sensitivity graphene-coated CL-20 composite material comprises the following steps: Step 1, ultrasonically dispersing a graphene material in a solvent A to obtain a graphene dispersion liquid I; Step 2, weighing a certain ratio of CL-20 and a surface modifier, adding them to the graphene dispersion liquid I and stirring so that CL-20 can fully adsorb the graphene material; Step 3, weighing the coating agent and dissolving it in solvent B to obtain coating liquid II, adding the coating liquid II dropwise to the graphene dispersion liquid I at a certain stirring speed and maintaining a certain temperature, during the dropping of the coating liquid II, the coating agent precipitates from the mixed solution and is coated on the surface of the solid particles, and after the dropping is completed, the stirring reaction is continued for a certain time, followed by filtering, washing, and drying to obtain a low-sensitivity graphene-coated CL-20 composite material.

[0005] The graphene material in step 1 is functionalized graphene; the amount of functionalized graphene added in step 1 is 0.5wt%-3wt% of the amount of CL-20.

[0006] In the step 1, the graphene material is at least one of graphene oxide, reduced graphene oxide, fluorinated graphene, long-chain graphene, isocyanate-treated graphene, and nitrogen-doped graphene.

[0007] The equipment used for the ultrasonic dispersion operation in step 1 is an ultrasonic cell pulverizer, the working mode is intermittent mode, the power is 0.8KW, and the ultrasonic time is 3-10min.

[0008] The amount of the surface modifier added in step 2 is 0.05wt%-0.5wt% of the amount of CL-20; the surface modifier in step 2 is selected from at least one of sodium dodecylbenzene sulfonate, KH550, and KH570.

[0009] In step 2, the stirring speed is 200 rpm to 400 rpm, and the adsorption time is 1.5 to 3 hours.

[0010] The amount of coating agent added in step 3 is 0.5wt%-2wt% of the amount of CL-20; the coating agent in step 3 is selected from at least one of polystyrene (PS), polyethylene oxide (PEO), polymethyl methacrylate (PMMA), and fluororubber (F26).

[0011] In step 1, the solvent A is at least one of deionized water, chloroform, cyclohexane and dichloromethane.

[0012] In step 3, the solvent B is at least one of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), acetone, acetonitrile, and ethyl acetate.

[0013] The volume ratio of the solvent A to the solvent B is 50:1-10:1.

[0014] In the step 3, the dropping speed of the coating liquid II is 0.1 mL / min to 3 mL / min, the heating temperature is 35° C. to 50° C., the stirring speed is 300 rpm to 450 rpm, and the stirring time is 2 to 4 h.

[0015] The second aspect of the present invention provides a graphene-coated CL-20 composite material, which is prepared by the preparation method of the low-sensitivity graphene-coated CL-20 described in the first aspect. The composite material is stable and has significantly lower sensitivity than the CL-20 raw material. It can be widely used in solid propellants, explosives, propellants, etc.

[0016] Compared with the prior art, the present invention has the following beneficial effects: Starting from the essential reason for the high sensitivity of CL-20 material, the present invention adds a functionalized graphene layer to block the energy transfer caused by external stimulation, and has a significant effect on reducing the sensitivity of CL-20 material. The present invention is based on the electrostatic adsorption of graphene and is supplemented by in-situ coating and fixation with surfactants and coating agents. This method can effectively solve the problems of low structural strength and short applicable period of products of traditional coating methods. The preparation method of the present invention is simple and the conditions are mild. It effectively overcomes the difficulties of cumbersome steps and low reaction safety factor of related methods, and also has certain guiding significance for subsequent industrial scale-up production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1These are SEM images of the CL-20 raw material (a) and the low-sensitivity graphene-coated CL-20 composite material (b) in Example 1. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without carrying out creative work are within the scope of protection of the present invention.

[0019] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0020] The experimental methods or test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0021] The present invention provides a method for preparing a low-sensitivity graphene-coated CL-20 composite material. Starting from the essential reason for the high sensitivity of the CL-20 material, the graphene-coated CL-20 composite material is obtained by electrostatic adsorption of the CL-20 material on functionalized graphene and in-situ coating and fixation of a surfactant and a coating agent. The method comprises the following steps: Step 1: Dispersing graphene materials to obtain graphene dispersion liquid I. Specifically, a certain amount of functionalized graphene is added to a container containing solvent A, and ultrasonically dispersed until the functionalized graphene is well dispersed.

[0022] Preferably, the equipment used for ultrasonic dispersion operation is an ultrasonic cell pulverizer, the working mode is intermittent mode, the power is 0.8KW, and the ultrasonic time is 3-10min.

[0023] In step 1, the graphene material is ultrasonically dispersed into the graphene dispersion liquid I using an ultrasonic cell crusher, and after standing for 15 minutes, no solid sedimentation occurs at the bottom of the container, which means that the graphene material is well dispersed.

[0024] In step 1, the graphene material is functionalized graphene, specifically at least one of graphene oxide, reduced graphene oxide, fluorinated graphene, long-chain graphene, isocyanate-treated graphene, and nitrogen-doped graphene.

[0025] In step 1, the amount of graphene added is 0.5wt%-3wt% of the amount of CL-20.

[0026] In step 1, solvent A is selected from at least one of deionized water, chloroform, cyclohexane, and dichloromethane.

[0027] Step 2: Graphene material adsorption to obtain a CL-20 suspension containing electrostatically adsorbed graphene material. Specifically, a certain ratio of CL-20 and a surface modifier are weighed and added to the graphene dispersion liquid I, and stirred to allow CL-20 to fully adsorb the graphene material to obtain a CL-20 suspension containing electrostatically adsorbed graphene material.

[0028] In step 2, the surface modifier is selected from at least one of sodium dodecylbenzene sulfonate, KH550, and KH570.

[0029] In step 2, the amount of surface modifier added is 0.05wt%-0.5wt% of the amount of CL-20; In step 2, the stirring speed is 200 rpm to 400 rpm, and the adsorption time is 1.5 to 3 h.

[0030] Preferably, the graphene dispersion is continuously stirred after adding CL-20 and the surface modifier. Due to electrostatic adsorption, the graphene dispersion gradually changes from black to transparent and the surface of the CL-20 particles changes from white to black, which indicates that the adsorption is complete.

[0031] Step 3, coating with a coating agent to obtain a low-sensitivity graphene-coated CL-20 composite material. Specifically, weigh the coating agent and dissolve it in solvent B to obtain a coating liquid II, and at a certain stirring speed, drop the coating liquid II into the graphene dispersion liquid I and keep a certain temperature constant. During the dropwise addition of the coating liquid II, the coating agent precipitates from the mixed solution and is coated on the surface of the solid particles. After the dropwise addition is completed, continue to stir and react for a certain time, then filter, wash, and dry to obtain a low-sensitivity graphene-coated CL-20 composite material.

[0032] In step 3, the coating agent is selected from at least one of polystyrene (PS), polyethylene oxide (PEO), polymethyl methacrylate (PMMA), and fluororubber (F26).

[0033] Preferably, the amount of coating agent added is 0.5wt%-2wt% of the amount of CL-20; In step 3, solvent B is at least one of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), acetone, acetonitrile, and ethyl acetate; Preferably, the volume ratio of solvent A to solvent B is 50:1-10:1; In step 3, the dropping speed of coating liquid II is 0.1 mL / min~3 mL / min, the heating temperature is 35°C~50°C, the stirring speed is 300 rpm~450 rpm, and the stirring time is 2~4 h.

[0034] The present invention also provides a low-sensitivity graphene-coated CL-20 composite material, which is prepared by the above-mentioned low-sensitivity graphene-coated CL-20 composite material preparation method.

[0035] The invention starts from the essential reason for the high sensitivity of CL-20 material, and obtains the graphene-coated CL-20 composite material by electrostatic adsorption of functionalized graphene by CL-20 material and in-situ coating and fixation by surfactant and coating agent; the material preparation method is simple, the product is stable, and the coating amount is low. Compared with the CL-20 raw material, the sensitivity is significantly reduced, and the application range of the material can be greatly improved.

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Sensitivity analysis test method for CL-20 material and low-sensitivity graphene-coated CL-20 composite material: Impact sensitivity (IS) test is carried out in accordance with the aerospace industry standard QJ20019_7_2018 "Composite Solid Propellant Safety Performance Test Method" Part 7: Drop Hammer Impact Sensitivity, and the characteristic drop height method is used to test the characteristic drop height and critical impact energy I of the sample at 50% explosion. 50 The test conditions are 21℃, 41%RH, 20mg of charge, 50cm of drop height, and 98N of hammer weight; the friction sensitivity (FS) test is carried out according to the aerospace industry standard QJ_20019.6_2018, the test conditions are 20℃, 46%RH, 20mg of charge, 90° of swing angle, 3.92MPa of pressure, and 25 times of test. The result is expressed as the explosion percentage P; the electrostatic sensitivity test is carried out according to the aerospace industry standard QJ20019-5-2018 "Test Method for Safety Performance of Composite Solid Propellants" Part 5: Electrostatic Spark Sensitivity, the test conditions are 15℃, 68%RH, 25mg of charge, electrode gap: 0.50mm, capacitance: 10000pF, and 30 times of test. The result is expressed as the excitation energy E 50 express. Example 1

[0038] Step 1, weighing 0.2 g of fluorinated graphene material, dispersing it in 500 ml of cyclohexane by ultrasonication for 5 min, to obtain a graphene dispersion liquid I; Step 2, weighing 30 g CL-20 and 0.03 g sodium dodecylbenzene sulfonate, adding them to the graphene dispersion I and stirring at a stirring speed of 300 rpm for 2 h to allow CL-20 to fully adsorb the graphene material; Step 3, weigh 0.6gF26 and dissolve it in 10ml acetone to obtain coating liquid II. Under a stirring speed of 300rpm, the coating liquid II is added dropwise to the graphene dispersion liquid I at a rate of 0.5mL / min and kept constant at 40°C. During the addition of coating liquid II, the coating agent precipitates from the mixed solution and is coated on the surface of the solid particles. After the addition is completed, the reaction is continued by stirring for 3h, and then filtered, washed and dried to obtain a low-sensitivity graphene-coated CL-20 composite material. The SEM image is as follows: Figure 1 As shown, the CL-20 raw material crystals have sharp edges, but after coating, the edges of the particles are weakened, and a small amount of cracks can be observed on the surface of individual particles, indicating the successful effect of the coating agent.

[0039] Equal amounts of CL-20 material and low-sensitivity graphene-coated CL-20 composite material were tested for sensitivity, and the results are shown in Table 1. The results show that the sensitivity of the low-sensitivity graphene-coated CL-20 composite material after coating is significantly lower than that of the CL-20 raw material, among which the friction sensitivity is reduced from 96% to 48%, the impact sensitivity is increased from 12.1J to 32.1J, and the electrostatic spark sensitivity is increased from 60mJ to 112.15mJ. This shows that the graphene coating method has a significant effect on reducing the sensitivity of the CL-20 sample. Example 2

[0040] Step 1, weighing 0.75 g of fluorinated graphene material, dispersing it in 800 ml of deionized water by ultrasonication for 10 min to obtain a graphene dispersion liquid I; Step 2, weighing 30 g CL-20 and 0.12 g KH550, adding them to the graphene dispersion I and stirring at a stirring speed of 350 rpm for 3 h to allow CL-20 to fully adsorb the graphene material; Step 3, weigh 0.15gPS and dissolve it in 20mlDMF to obtain coating liquid II. Under a stirring speed of 300rpm, the coating liquid II is added dropwise to the graphene dispersion liquid I at 1mL / min and kept constant at 50°C. During the addition of coating liquid II, the coating agent precipitates from the mixed liquid and is coated on the surface of the solid particles. After the addition is completed, the reaction is continued to stir for 4h, and then filtered, washed, and dried to obtain a low-sensitivity graphene-coated CL-20 composite material.

[0041] Equal amounts of CL-20 material and low-sensitivity graphene-coated CL-20 composite material were tested for sensitivity, and the results are shown in Table 1. The results show that the sensitivity of the low-sensitivity graphene-coated CL-20 composite material after coating is significantly lower than that of the CL-20 raw material, among which the friction sensitivity is reduced from 96% to 40%, the impact sensitivity is increased from 12.1J to 35.4J, and the electrostatic spark sensitivity is increased from 60mJ to 154.45mJ. Example 3

[0042] Step 1, weighing 0.3 g of nitrogen-doped graphene, dispersing it in 500 ml of dichloromethane by ultrasonication for 6 min to obtain a graphene dispersion I; Step 2, weighing 30 g CL-20 and 0.15 g KH550, adding them to the graphene dispersion I and stirring at a stirring speed of 300 rpm for 3 h to allow CL-20 to fully adsorb the graphene material; Step 3, weigh 0.5gF26 and dissolve it in 15ml acetonitrile to obtain coating liquid II. Under a stirring speed of 300rpm, the coating liquid II is added dropwise to the graphene dispersion liquid I at 0.5mL / min and kept constant at 35°C. During the addition of coating liquid II, the coating agent precipitates from the mixed solution and is coated on the surface of the solid particles. After the addition is completed, the stirring reaction is continued for 3h, and then filtered, washed, and dried to obtain a low-sensitivity graphene-coated CL-20 composite material.

[0043] Equal amounts of CL-20 material and low-sensitivity graphene-coated CL-20 composite material were tested for sensitivity, and the results are shown in Table 1. The results show that the sensitivity of the low-sensitivity graphene-coated CL-20 composite material after coating is significantly lower than that of the CL-20 raw material, among which the friction sensitivity is reduced from 96% to 52%, the impact sensitivity is increased from 12.1J to 28.0J, and the electrostatic spark sensitivity is increased from 60mJ to 103.85mJ. Example 4

[0044] Step 1, weighing 0.3 g of long-chain graphene, dispersing it in 500 ml of chloroform by ultrasonication for 8 min, to obtain a graphene dispersion I; Step 2, weighing 30 g CL-20 and 0.05 g sodium dodecylbenzene sulfonate, adding them to the graphene dispersion I and stirring at a stirring speed of 300 rpm for 2 h to allow CL-20 to fully adsorb the graphene material; Step 3, weigh 0.6gPMMA and dissolve it in 10ml acetone to obtain coating liquid II. Under a stirring speed of 300rpm, the coating liquid II is added dropwise to the graphene dispersion liquid I at 0.2mL / min and kept constant at 40°C. During the addition of coating liquid II, the coating agent precipitates from the mixed liquid and is coated on the surface of the solid particles. After the addition is completed, the stirring reaction is continued for 3h, and then filtered, washed, and dried to obtain a low-sensitivity graphene-coated CL-20 composite material.

[0045] Equal amounts of CL-20 material and low-sensitivity graphene-coated CL-20 composite material were tested for sensitivity, and the results are shown in Table 1. The results show that the sensitivity of the low-sensitivity graphene-coated CL-20 composite material after coating is significantly lower than that of the CL-20 raw material, among which the friction sensitivity is reduced from 96% to 48%, the impact sensitivity is increased from 12.1J to 29.2J, and the electrostatic spark sensitivity is increased from 60mJ to 120.54mJ. Example 5

[0046] Step 1, weighing 0.4 g of isocyanate-treated graphene, dispersing it in 600 ml of cyclohexane by ultrasonic treatment for 6 min, to obtain a graphene dispersion liquid I; Step 2, weighing 30 g CL-20 and 0.3 g KH570, adding them to the graphene dispersion I and stirring at a stirring speed of 300 rpm for 2 h to allow CL-20 to fully adsorb the graphene material; Step 3, weigh 0.4g PEO and dissolve it in 10ml DMF to obtain coating liquid II. Under a stirring speed of 300rpm, the coating liquid II is added dropwise to the graphene dispersion liquid I at 0.1mL / min and kept constant at 45°C. During the addition of coating liquid II, the coating agent precipitates from the mixed liquid and is coated on the surface of the solid particles. After the addition is completed, the stirring reaction is continued for 3h, and then filtered, washed, and dried to obtain a low-sensitivity graphene-coated CL-20 composite material.

[0047] Equal amounts of CL-20 material and low-sensitivity graphene-coated CL-20 composite material were tested for sensitivity, and the results are shown in Table 1. The results show that the sensitivity of the low-sensitivity graphene-coated CL-20 composite material after coating is significantly lower than that of the CL-20 raw material, among which the friction sensitivity is reduced from 96% to 60%, the impact sensitivity is increased from 12.1J to 41.8J, and the electrostatic spark sensitivity is increased from 60mJ to 135.42mJ.

[0048] Table 1

[0049] The above description is only an exemplary embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a low-sensitivity graphene-coated CL-20 composite material, characterized in that: The following steps are involved: Step 1, ultrasonically dispersing a graphene material in a solvent A to obtain a graphene dispersion liquid I; Step 2, weighing a certain ratio of CL-20 and a surface modifier, adding them to the graphene dispersion liquid I and stirring so that CL-20 can fully adsorb the graphene material; Step 3, weighing the coating agent and dissolving it in solvent B to obtain coating liquid II, adding the coating liquid II dropwise to the graphene dispersion liquid I at a certain stirring speed and maintaining a certain temperature, during the dropping of the coating liquid II, the coating agent precipitates from the mixed solution and is coated on the surface of the solid particles, and after the dropping is completed, the stirring reaction is continued for a certain time, followed by filtering, washing, and drying to obtain a low-sensitivity graphene-coated CL-20 composite material.

2. The method for preparing the low-sensitivity graphene-coated CL-20 composite material according to claim 1, characterized in that: The graphene material in step 1 is functionalized graphene; the amount of functionalized graphene added in step 1 is 0.5wt%-3wt% of the amount of CL-20.

3. The method for preparing the low-sensitivity graphene-coated CL-20 composite material according to claim 2, characterized in that: In the step 1, the graphene material is at least one of graphene oxide, reduced graphene oxide, fluorinated graphene, long-chain graphene, isocyanate-treated graphene, and nitrogen-doped graphene.

4. The method for preparing the low-sensitivity graphene-coated CL-20 composite material according to claim 1, characterized in that: The equipment used for the ultrasonic dispersion operation in step 1 is an ultrasonic cell pulverizer, the working mode is intermittent mode, the power is 0.8KW, and the ultrasonic time is 3-10min.

5. The method for preparing the low-sensitivity graphene-coated CL-20 composite material according to claim 1, characterized in that: The amount of the surface modifier added in step 2 is 0.05wt%-0.5wt% of the amount of CL-20; the surface modifier in step 2 is selected from at least one of sodium dodecylbenzene sulfonate, KH550, and KH570.

6. The method for preparing the low-sensitivity graphene-coated CL-20 composite material according to claim 1, characterized in that: In step 2, the stirring speed is 200 rpm to 400 rpm, and the adsorption time is 1.5 to 3 hours.

7. The method for preparing the low-sensitivity graphene-coated CL-20 composite material according to claim 1, characterized in that: The amount of coating agent added in step 3 is 0.5wt%-2wt% of the amount of CL-20; the coating agent in step 3 is selected from at least one of polystyrene (PS), polyethylene oxide (PEO), polymethyl methacrylate (PMMA), and fluororubber (F26).

8. The method for preparing the low-sensitivity graphene-coated CL-20 composite material according to claim 1, characterized in that: In step 1, the solvent A is at least one of deionized water, chloroform, cyclohexane, and dichloromethane; In step 3, solvent B is at least one of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), acetone, acetonitrile, and ethyl acetate; The volume ratio of the solvent A to the solvent B is 50:1-10:

1.

9. The method for preparing the low-sensitivity graphene-coated CL-20 composite material according to claim 1, characterized in that: In the step 3, the dropping speed of the coating liquid II is 0.1 mL / min to 3 mL / min, the heating temperature is 35° C. to 50° C., the stirring speed is 300 rpm to 450 rpm, and the stirring time is 2 to 4 h.

10. A low-sensitivity graphene-coated CL-20 composite material prepared by the preparation method according to any one of claims 1 to 9.

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