A method for improving the slow-baking heat resistance of explosives based on energetic negative burning rate catalyst

Abstract

The present invention provides a method for improving the slow-baking heat resistance of explosives based on an energetic negative burning rate catalyst, the method adopts ZIF-90 as an energetic negative burning rate catalyst, the explosive includes LLM-105 elemental explosive, and the slow-baking heat resistance of explosives is improved by regulating the burning rate of explosives by the negative burning rate catalyst. In the present invention, a 5% mass fraction of ZIF-90 can produce a relatively excellent negative catalytic effect on the LLM-105 energetic material, so that the thermal decomposition temperature of LLM-105 is lagged by 6.4°C. In order to verify the universality of this energetic negative burning rate catalyst, after adding a 5% mass fraction of ZIF-90 to an LLM-105-based explosive column, the heat-resistant insensitive characteristics of the explosive column can be significantly improved, so that the heat-resistant time of the LLM-105-based explosive column is increased by more than 1 times compared with before.

Description

Technical Field

[0001] The invention belongs to the technical field of energetic materials, relates to the slow-baking heat resistance of explosives, and specifically relates to a method for improving the slow-baking heat resistance of explosives based on an energetic negative burning rate catalyst. Background Art

[0002] High energy density and high energy release rate are the eternal pursuit of the development of explosives. Developing new high-energy density energetic materials is the primary material basis for improving the power, power and firepower of weapons and equipment, and is a prerequisite for the renewal of weapons and equipment. However, "there is no combat effectiveness without survival". High energy density is often accompanied by low safety. How to solve the contradiction between energy and safety is a difficult problem that energetic material researchers urgently need to solve. In modern warfare, the increasingly harsh battlefield environment has put forward higher requirements on the battlefield survivability of combat personnel and weapon platforms. It is urgent to improve the safety of weapons and ammunition and their anti-strike and anti-detonation performance. In recent years, heat-resistant insensitive high-energy explosives have been the trend of weapon development at home and abroad. The use of heat-resistant single explosives that are insensitive to external effects as the main charge has become one of the important research directions in the field of energetic materials. In the military field: hypersonic weapons have become one of the "heavy weapons of major powers" for various military powers to maintain a strong strategic deterrence. With the advancement of hypersonic weapon projects and models, and the gradual formation of combat capabilities, a new combat style will emerge in the future, which will profoundly change the world's military power structure. The recent actual combat application of Russian hypersonic weapons and the successful test launch of various types of missiles have made the major military powers in the world pay more attention to and have a sense of urgency about hypersonic weapons. The relevant research and testing activities have become more intensive, and the investment in the future has been increased. Although hypersonic weapons have achieved their penetration advantage by relying on their active systems, the energy performance of the heat-resistant explosives in the warheads of hypersonic weapons is the key to whether they can exert their destructive power. In addition, most of the heat-resistant explosives currently used have the defect of low energy. If they are used, the destructive advantage of hypersonic weapons cannot be exerted, which greatly hinders the further development of hypersonic weapons. In the civilian field: With the continuous deepening of oil and gas field development, the development of dense oil and gas reservoirs has gradually entered, and the investment has gradually increased. The dense formation has the characteristics of high strength and high fracture pressure after perforation. In order to improve the efficiency of oil and natural gas extraction, it is necessary to vigorously develop oil and gas well perforation technology. The key to this technology lies in the explosives in the perforation. At present, the perforating bullets used in large quantities in oil fields are ordinary perforating bullets with low energy performance, which are powerless for deep well drilling. Therefore, it is urgent to develop high-density and high-detonation-velocity explosives as perforating bullet charges, which has become one of the important directions for promoting the development of oil perforating bullets. However, high energy means high sensitivity, which poses great safety risks during use.

[0003] Literature research The present invention found that 2,6-diamino-3,5-dinitropyridine-1-oxide (LLM-105) is a typical representative of high-energy insensitive explosives in recent years. Its synthesis was reported by the Lawrence Livermore National Laboratory in the United States in 1995. LLM-105 has a bright yellow needle-shaped crystal appearance and a density of 1.913 g / cm 3 , oxygen balance is -37.03%, exothermic peak temperature is 342℃, and theoretical detonation velocity under crystal density is 8560m / s. Research has found that the energy of LLM-105 is about 20% higher than that of triaminotrinitrobenzene (TATB), its sensitivity is equivalent to trinitrotoluene (TNT), and its heat resistance is equivalent to hexanitrostilbene (HNS). It is a high-energy insensitive explosive with superior comprehensive performance, high thermal stability in a wide temperature range, and very insensitive to shock waves, sparks and friction impacts. It has broad application prospects in heat-resistant insensitive ammunition systems.

[0004] However, there is still a major flaw in the current application of LLM-105-based heat-resistant explosives: when LLM-105-based explosives are made into columns, they will explode after being slowly baked at 250°C for about 50 minutes, which makes it difficult to meet the needs of hypersonic weapons and deep well perforating bullets. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for improving the slow-baking heat resistance of explosives based on an energetic negative burning rate catalyst, so as to solve the technical problem that the slow-baking heat resistance of LLM-105-based explosives in the prior art needs to be further improved.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0007] A method for improving the slow-baking heat resistance of explosives based on an energetic negative burning rate catalyst. The method uses ZIF-90 as an energetic negative burning rate catalyst. The explosive includes LLM-105 single-substance explosive. The negative burning rate catalyst regulates the burning rate of the explosive to improve the slow-baking heat resistance of the explosive.

[0008] The present invention also has the following technical features:

[0009] The added amount of the energetic negative burning rate catalyst is 5% of the total weight of the explosive column corresponding to the explosive containing the energetic negative burning rate catalyst.

[0010] The explosive is composed of the following raw materials by weight: 90% of LLM-105 elemental explosive, 5% of binder, and 5wt% of ZIF-90.

[0011] The binder is hydroxyl-terminated polybutadiene.

[0012] The energetic negative burning rate catalyst causes the thermal decomposition temperature of the explosive to lag by 6.4°C.

[0013] Compared with the prior art, the present invention has the following technical effects:

[0014] (I) The synthesis method of the energetic negative combustion rate catalyst ZIF-90 used in the present invention has the characteristics of simple and convenient operation conditions and mild experimental conditions, and there is no relevant report on ZIF-90 as an energetic negative combustion rate catalyst. ZIF-90 is used as a potential green and insensitive energetic negative combustion rate catalyst in the present invention, and it is expected to have great application prospects in the field of heat-resistant insensitive energetic materials in the future. It is in line with the concept of "green" synthesis of energetic materials.

[0015] (II) The present invention uses 5% ZIF-90 by mass to produce a relatively excellent negative catalytic effect on the LLM-105 energetic material, and the thermal decomposition temperature of LLM-105 is delayed by 6.4°C. In order to verify the universality of this energetic negative burning rate catalyst, the addition of 5% ZIF-90 by mass to the LLM-105-based explosive column can significantly improve the heat-resistant insensitive characteristics of the explosive column, and the heat-resistant time of the LLM-105-based explosive column is increased by more than 1 times compared with before.

[0016] (III) The measured sensitivity of the energetic negative combustion rate catalyst of the present invention is relatively low. After 5% ZIF-90 is uniformly mixed with the LLM-105 energetic material, the friction and impact sensitivities of the LLM-105 energetic material can be reduced to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a single crystal simulation diagram of LLM-105.

[0018] Figure 2 Measured and simulated XRD patterns of ZIF-90.

[0019] Figure 3 This is the infrared spectrum of ZIF-90.

[0020] Figure 4 This is a scanning electron microscope image of ZIF-90.

[0021] Figure 5 This is the thermal decomposition diagram of ZIF-90 alone.

[0022] Figure 6 This is a comparison diagram of the thermal decomposition of LLM-105 after adding ZIF-90.

[0023] Figure 7 Kinetic diagram of ZIF-90+LLM-105 at different heating rates.

[0024] Figure 8 This is the α-T curve of the thermal decomposition conversion rate (α) of ZIF-90+LLM-105 material changing with temperature.

[0025] Fig. 9 The charge column 1 is composed of 95% LLM-105 single-substance explosive and 5% binder.

[0026] Fig.10 The charge column 2 is composed of 90% LLM-105 single-element explosive, 5% ZIF-90 and 5% binder.

[0027] Fig.11 This is the picture of the drug column 1 after the slow baking experiment.

[0028] Fig.12 This is the picture of the drug column 2 after the slow baking experiment.

[0029] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0030] It should be noted that, unless otherwise specified, all raw materials in the present invention are raw materials known in the prior art.

[0031] The overall technical concept of the present invention: The present invention proposes the concept of energetic negative combustion rate catalyst, designs a simple, convenient and easy-to-synthesize "energetic negative combustion rate catalyst" to catalyze LLM-105, so that its decomposition peak temperature is pushed back and the slow baking performance is improved. Therefore, this embodiment selects ZIF-90, which has the advantages of large specific surface area, uniform pore structure, high hydrothermal stability and chemical stability, easy modification and simple synthesis, as the "energetic negative combustion rate catalyst". ZIF-90 has the following advantages: on the one hand, the large specific surface area can make ZIF-90-based EMOFs and components of energetic materials such as HMX more fully contact, and the different interactions between organic ligands and metal centers will affect the structural evolution of the catalyst during the combustion catalytic reaction; on the other hand, the regular pore structure can make the particle size distribution of ZIF-90-based EMOFs uniform, and it is easier to change the decomposition process of energetic materials in the subsurface reaction zone or on the combustion surface, and play a uniform synergistic catalytic role at the molecular level, which can greatly affect the thermal decomposition rate of the catalyzed energetic materials, thereby playing an effective catalytic role. In addition, since ZIF-90-based EMOFs contain unreacted aldehyde groups, the aldehyde groups will be oxidized and absorb some heat, thus increasing the peak temperature of thermal decomposition of energetic materials during the catalytic reaction. ZIF-90 has a medium carbon content and is a catalyst bed that is rich in metallic zinc, etc. It has the effect of blocking the condensation of metallic zinc, and can inhibit the escape of gases such as aldehydes, NO, and NO2, allowing them to fully react in the condensed phase. It has a catalytic effect and is an efficient reducing agent for substances such as NO, NO2, and ZnO. Therefore, ZIF-90 fully meets the requirements of an "energetic negative combustion rate catalyst."

[0032] Therefore, the present invention selects a strategy to improve the slow-baking heat resistance of LLM-105-based explosive columns: the slow-baking heat resistance of LLM-105-based explosive columns is improved through the concept of "energetic negative burning rate catalyst".

[0033] In the present invention, the single crystal simulation diagram of LLM-105 is as follows Figure 1 As shown. The structural formula of LLM-105 is:

[0034]

[0035] In the present invention, ZIF-90 uses ZIF-90 known in the prior art. Preferably, in the present invention, ZIF-90 is synthesized in one step by Zn(NO3)2·6H2O and imidazole-2-carboxaldehyde. More preferably, the specific synthesis steps of ZIF-90 are:

[0036] a) Weigh 2.1 g of 2-formaldehyde imidazole and 1.0 g of additive polyvinylpyrrolidone (PVP) respectively, add 100 mL of deionized water, and mix by ultrasonication for 12 min until uniform. Set aside.

[0037] b) Weigh 3.2 g of Zn(NO3)2·6H2O and add 120 mL of tert-butyl alcohol solution, sonicate for 10 min until completely dissolved, and set aside.

[0038] c) Mix the prepared solutions a and b and reflux at 90°C for 5 min.

[0039] d) After the final ultrasonic reaction accompanied by vigorous stirring for 5 minutes, the mixture was centrifuged at 10,000 rpm for 5 minutes, the supernatant was removed, and the mixture was washed with water and methanol in turn, and then freeze-dried. The final orange-yellow powder obtained was ZIF-90, with a yield of 90%.

[0040] Figure 2 Measured and simulated XRD patterns of ZIF-90. Figure 3 This is the infrared spectrum of ZIF-90. Figure 4 This is a scanning electron microscope image of ZIF-90. Figures 2 to 4 From the characterization, it can be seen that the product obtained by the above synthesis method is the target product ZIF-90.

[0041] In accordance with the above technical scheme, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention.

[0042] Example:

[0043] This embodiment provides a method for improving the slow-baking heat resistance of explosives based on an energetic negative burning rate catalyst. The method uses ZIF-90 as an energetic negative burning rate catalyst. The explosive is an LLM-105-based explosive. The slow-baking heat resistance of the explosive is improved by adjusting the burning rate of the explosive with the negative burning rate catalyst.

[0044] In order to further investigate the application scope of ZIF-90 in the field of heat-resistant explosives, this example adds ZIF-90 to the typical LLM-105 explosive formula in service, conducts a slow-baking heat resistance test on the LLM-105 heat-resistant explosive column, and investigates its heat-resistant insensitive catalytic properties.

[0045] Grain 1: The sample is composed of 95wt% LLM-105 single explosive and 5wt% binder hydroxyl-terminated polybutadiene (HTPB), the sample size is 20×30mm, and the molding pressure is 2500. The test temperature range is 30~500℃, and the grain assembly is as follows Fig. 9 shown.

[0046] Grain 2: The sample is composed of 90wt% LLM-105 single explosive, 5wt% ZIF-90 and 5wt% binder hydroxyl-terminated polybutadiene (HTPB), the sample size is 20×30mm, and the molding pressure is 2500. The test temperature range is 30~500℃, and the grain assembly is as follows Fig.10 shown.

[0047] In this embodiment, the experimental steps of heat resistance slow baking of LLM-105 based explosive column are as follows:

[0048] Test steps:

[0049] a. Open the end cover on one side of the medicine column and put the weighed sample into the slow-baked medicine column;

[0050] b. Install the temperature sensor on the medicine column;

[0051] c. Install the heating jacket outside the medicine column;

[0052] d. Connect the heating power line and the temperature measuring line;

[0053] e. Turn on the main power of the temperature control box and set the temperature control program on the computer (heat up to 200℃ at 3℃ / min, and heat up to 500℃ at 1℃ / min);

[0054] f. Record the decomposition temperature and reaction intensity of the sample throughout the entire process (if an explosion occurs during the experiment, the experiment will be terminated).

[0055] Slow-baking heat resistance test results:

[0056] Grain column 1: The temperature was raised to 200℃ at 3℃ / min, and then to 250℃ at 1℃ / min. No obvious reaction occurred when the temperature was kept constant at 250℃ for 40min. After 50min, the explosion occurred and the charge shell was ruptured. The picture of the tested grain column is as follows: Fig.11 shown.

[0057] Grain column 2: The temperature was raised to 200℃ at 3℃ / min, and then to 250℃ at 1℃ / min. No obvious reaction occurred when the temperature was kept constant at 250℃ for 2.0h. When the temperature was raised to 320℃, a combustion reaction occurred, and both ends of the charge shell were broken open. The finished grain column is shown in the figure below. Fig.12 shown.

[0058] From the comparison between the above-mentioned powder column 1 and powder column 2, it can be seen that when a catalytic amount of ZIF-90 is added to the LLM-105-based explosive powder column, it can be seen in the slow-baking heat resistance test of the powder column that ZIF-90 can greatly improve the heat resistance of the powder column, so that the combustion reaction will not occur until the LLM-105-based explosive powder column is heated to 320°C, rather than a violent explosion. This shows that ZIF-90, as a negative burning rate catalyst, can produce relatively excellent heat-resistant and insensitive catalytic properties for explosive formulations, which further verifies the conjecture of this embodiment. This also lays a solid foundation for the promotion and application of this energetic negative burning rate catalyst. This research has great subversive significance both in scientific research and in the military.

[0059] The present invention introduces the concept of "energetic negative burning rate catalyst" in the field of heat-resistant and insensitive explosives, and reports a green energetic negative burning rate catalyst ZIF-90. ZIF-90 is a zeolite imidazolate framework material, which has the advantages of large specific surface area, uniform pore structure, high hydrothermal stability and chemical stability, easy modification and simple synthesis, and there is no related report on ZIF-90 as an energetic negative burning rate catalyst. The method for synthesizing the energetic negative burning rate catalyst ZIF-90 of the present invention has the advantages of simple and convenient experimental steps and mild experimental conditions.

[0060] The application of this green energetic negative burning rate catalyst in the field of heat-resistant insensitive LLM-105 explosives will have the following advantages:

[0061] On the one hand, the thermal decomposition diagram of ZIF-90 alone is as follows Figure 5 As shown in the figure, the thermal decomposition comparison of LLM-105 after adding ZIF-90 is shown in Figure 6 As shown, the kinetic diagrams of ZIF-90+LLM-105 at different heating rates are shown in Figure 7 As shown in the figure, the α-T curve of the thermal decomposition conversion rate (α) of ZIF-90+LLM-105 material changes with temperature is shown in Figure 8 When the addition amount of the burning rate catalyst is only 5% (mass fraction), the peak temperature of thermal decomposition of LLM-105-based energetic materials can be increased, producing a relatively excellent catalytic effect, such as Figure 6 As shown, the thermal decomposition peak temperature lags by 6.4°C.

[0062] On the other hand, it can be seen from Table 1 and Table 2 that the measured sensitivity of this energetic negative burning rate catalyst is relatively low (impact sensitivity>40J; friction sensitivity>360N). After 5% ZIF-90 is evenly mixed with LLM-105 energetic material, the friction and impact sensitivity of LLM-105 energetic material can be reduced to a certain extent. In addition, ZIF-90 can greatly improve the heat resistance of the explosive column. After adding 5% catalytic amount of ZIF-90 to LLM-105-based explosive column, the heat resistance of the explosive column can be significantly improved, and the heat resistance of the explosive column is increased by more than 1 times. Therefore, ZIF-90, as a potential green, insensitive energetic negative burning rate catalyst, is expected to have great application prospects in the field of heat-resistant insensitive energetic materials in the future.

[0063] Table 1 Kinetic parameters of LLM-105+ZIF-90 calculated by Kissinger method, Friedman method and combined kinetic method

[0064]

[0065] Table 2. Sensitivity comparison of LLM-105 after adding ZIF-90

[0066] name Impact sensitivity (J) Friction sensitivity(N) LLM-105+ZIF-90(LLM-105) ＞40(26) ＞360(353) ZIF-90 ＞40 ＞360

Claims

1. A method for improving the slow-baking heat resistance of explosives based on an energetic negative burning rate catalyst, characterized in that: The method uses ZIF-90 as an energetic negative burning rate catalyst, the explosive includes LLM-105 single explosive, and the slow-baking heat resistance of the explosive is improved by adjusting the burning rate of the explosive with the energetic negative burning rate catalyst; The added amount of the energetic negative burning rate catalyst is 5% of the total weight of the explosive column corresponding to the explosive containing the energetic negative burning rate catalyst.

2. The method for improving the slow-baking heat resistance of explosives based on an energetic negative burning rate catalyst as claimed in claim 1, characterized in that: The explosive is composed of the following raw materials by weight: 90% of LLM-105 single-substance explosive, 5% of binder, and 5% of ZIF-90.

3. The method for improving the slow-baking heat resistance of explosives based on an energetic negative burning rate catalyst as claimed in claim 2, characterized in that: The binder is hydroxyl-terminated polybutadiene.

4. The method for improving the slow-baking heat resistance of explosives based on an energetic negative burning rate catalyst as claimed in claim 1, characterized in that: The energetic negative burning rate catalyst causes the thermal decomposition temperature of the explosive to lag by 6.4°C.

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